Sim vs Retool
Sim is the open-source AI workspace where teams build, deploy, and manage AI agents visually, conversationally, or with code. Here is how Sim compares to Retool on platform architecture, AI capabilities, integrations, pricing, security, and support. Every fact below is sourced and dated.
Sim is an open-source AI workspace for building, deploying, and managing AI agents. This page compares Sim to Retool across platform architecture, AI capabilities, integrations, pricing, security and compliance, observability, and support, using sourced, dated facts for buyers evaluating both platforms.
What is Sim?
Sim is the open-source AI workspace where teams build, deploy, and manage AI agents, connecting 1,000+ integrations and every major LLM to automate real work visually, conversationally, or with code.
What is Retool?
Retool is a low-code platform for building, deploying, and managing internal software (apps, workflows, and AI agents) that connect to databases, APIs, and LLMs.
Sim vs Retool: feature-by-feature comparison
CompareSim vs Retool
Sim
Retool
Platform
Builder type
Sim
Visual canvas, chat, or codeVisual drag-and-drop canvas, natural-language (Chat), or code (API/SDK)
Retool
Low-code builder with AI-generated starting pointsLow-code/no-code visual app and workflow builder with an underlying React-based app runtime; supports AI-generated ("AppGen") starting points that users then refine visually or by editing generated queries/code.. Retool offers a React-based app builder where you can generate pages, components, and queries from a natural-language description and then edit the underlying logic directly.
Learning curve
Sim
Low, plus natural-language Chat for non-technical usersLow for visual building; natural-language Chat surface for non-technical builders. Chat lets users describe a workflow in plain language and have Sim build it.
Retool
Not publicly documentedUnknown. Retool has not published a learning-curve claim.
Self-hosting
Retool
Yes: self-hosted deployment is available on Free, Team, and Business plans at the same pricing as cloud; Enterprise is required for unlimited users and advanced capabilities. A Retool-issued license key is required even when self-hosted.. Self-hosted Retool is deployable via Docker (non-production/testing only) or Kubernetes/Helm (production).
Deployment options
Sim
Cloud-hosted or self-hosted, no mid-tier VPC optionCloud-hosted (managed, multi-tenant SaaS) or self-hosted (Docker/Kubernetes). No documented managed single-tenant/VPC hosting tier in between. The Enterprise plan's only hosting-related row in the pricing comparison table is a boolean "Self Hosting" flag; there is no dedicated-instance/VPC offering.
Retool
Cloud, or self-hosted via Docker/KubernetesRetool Cloud (multi-tenant SaaS), or self-hosted via Docker Compose (non-prod/testing) or Kubernetes with Helm chart (production).
Templates
Sim
License
Sim
Apache 2.0Apache License 2.0
Retool
Closed-source, license key requiredProprietary. Retool is closed-source and proprietary for both cloud and self-hosted versions. The self-hosted codebase can be forked and customized and bundles third-party open-source dependencies, but requires a Retool license key to run.
Environment promotion
Sim
Yes: fork a whole workspace into a dev/qa/prod-style child, diff it, and promote or roll back changes in either direction. Credential and env-var remapping is required before every promote, so secrets are never silently copied across environments. Gated to Enterprise plan on hosted Sim, or a FORKING_ENABLED flag on self-hosted deployments.
Retool
Yes: via Retool Source Control (Git-based) across separate instances/spaces. Source Control lets teams branch an app, open pull requests, and merge changes across dev, staging/QA, and production, running on separate Retool instances (self-hosted Enterprise) or Retool Spaces (Cloud) with per-app control over what syncs. It targets Enterprise/self-hosted customers and requires connecting an external Git provider (GitHub, GitLab, or CodeCommit).
Version control
Sim
Deployment rollback plus Copilot edit diff/revertDeployed-version history with rollback for every workflow; server-persisted checkpoint/revert and visual diff (accept/reject) specifically for Copilot AI edits. Manual drag-and-drop undo/redo is client-side/localStorage only (capped at 100 ops, 5 stacks), not server-synced across devices. Deployment history does not include an arbitrary version-to-version diff tool, and knowledge base documents have no version history.
Retool
Branching, PR review, and release historyBranch-based editing, pull-request review, and release history for controlling which version is live, plus rollback and blue/green deployments.. Source Control supports branch-based editing that isolates changes without overwriting teammates, pull-request review before merging into a live app, and Retool Releases to control which Git commit is live vs draft. No dedicated diff/compare view or client-vs-server undo/redo distinction exists.
Realtime collaboration
Sim
Retool
Yes: Retool Multiplayer lets multiple people edit the same app at once, with live avatars and highlights showing where each teammate is working. It is generally available on Cloud and in beta for self-hosted. Under the hood it uses conflict-free replicated data types (CRDTs) over WebSockets so simultaneous edits merge automatically instead of overwriting each other.. Self-hosted customers must sign up for beta access.
Native file storage
Sim
Yes: a native Files area with folder hierarchy, link-based sharing (public, password, email OTP, or SSO auth), and a workspace-level Recently Deleted view covering workflows, tables, knowledge bases, files, and folders. Admins can restrict which share-auth modes (public/password/email/SSO) a permission group is allowed to use.
Retool
Partial, folders and links yes, no trash/recovery or password links foundPartial: Retool Storage is a native Retool-hosted file store (cloud orgs) supporting folder creation/rename/delete, file rename/move, and link-based access (public URLs or app-scoped private URLs). No password-protected/SSO-gated sharing links or deleted-item/trash recovery mechanism is documented.. Storage caps at a fixed capacity and lacks more advanced sharing and recovery controls.
Sub-workflows (composition)
Sim
Retool
Yes: the Workflow block runs another saved workflow as a step, passing data to it and receiving its returned data back, so the parent workflow can compose child workflows rather than duplicating logic.. The Workflow block supports two execution modes: Finished, where the calling workflow pauses until the triggered workflow run completes, and Queued, where the calling workflow continues immediately while the triggered run is queued.
Pricing
Pricing model
Sim
Credit-based billing, BYOK exempt from capsCredit-based usage billing (Stripe), with bring-your-own-key exemption from metered caps
Retool
Seat-based plus AI credits and hourly Agents billingSeat-based (separate builder vs. end-user/internal-user seat prices) plus pooled monthly AI-credit allocations and separately metered hourly billing for Agents usage.
Entry paid plan
Sim
Pro plan at $25/user/monthPro: $25 per user/month
Retool
$10/builder + $5/user per month (Team plan)Team plan: $10/builder/month and $5/internal-user/month (annual billing; $12/$7 monthly), including 5,000 workflow runs/month, staging environment, app release versions, and 1,000 AI credits/month.
Free tier
Sim
Bring your own key
Sim
Retool
BYO chat model, but embeddings always use OpenAIPartial: Retool AI supports "bring your own" model connections for chat/completion models (OpenAI, Anthropic, Google, AWS, Azure, or custom), but Retool Vectors' embedding calls always go through OpenAI's API regardless of the chosen chat model.
Security & compliance
SOC 2
Data residency
Sim
Full control via self-hosting; Cloud region toggle is global, not per-customerFull data control via self-hosting (Docker/Kubernetes); data never leaves customer infrastructure when self-hosted. On Sim Cloud, async job execution has an internal US/EU region toggle, but it is deployment-wide, not a customer-selectable per-workspace residency option
Retool
AWS-hosted (cloud); no data stored self-hostedCloud: customer data stored redundantly across multiple AWS data center locations (no customer-selectable region specified). Self-hosted: no Retool systems store customer data and no Retool personnel have technical/logical access to it.
Role-based access control
Audit logging
Sim
Additional compliance
Sim
SOC2SOC2. Self-hosting is the primary lever Sim offers for data-residency-sensitive compliance needs beyond SOC2, rather than additional certifications.
Retool
SOC 2, ISO 27001, GDPR, CCPA; HIPAA via BAASOC 2 Type II, ISO/IEC 27001:2022, GDPR, and CCPA certifications, plus HIPAA via BAA on Enterprise.. The Trust Center (SafeBase-powered) lists SOC 2 Type 2, ISO/IEC 27001:2022, GDPR, and CCPA certifications. HIPAA compliance is available with a signed BAA on Enterprise (self-hosted) plans. PCI and FedRAMP are not confirmed.
Model & tool governance
Sim
Yes: enterprise "permission groups" let an admin allow-list/deny-list specific LLM providers and models, and separately deny specific tools/integrations (or disable all MCP or custom tools) per group, layered on top of workspace admin/write/read roles. This does not control whether an LLM provider retains prompts. Sim offers no "zero data retention" mode or governed AI gateway. A separate, Enterprise-gated feature lets orgs set a log-retention window and redact PII, but that only controls how long Sim itself keeps execution logs.
Retool
Not publicly documentedUnknown. Not publicly documented.
Credential governance
Sim
Yes: shared credentials (connected accounts, service accounts, workspace secrets) are their own nested permission level (Member/Admin) below organization and workspace roles, and enterprise permission groups can further allow-list specific integrations and restrict which file-share auth modes (public/password/email/SSO) a group may use. A user's personal environment variables/secrets are never shared or inherited by anyone, including org owners/admins.
Retool
Yes: Retool (Business/Enterprise plans) supports resource-level permissions with Use, Edit, and Own tiers. Enterprise orgs can go further and set per-environment permissions on the same resource (for example, allow Use on staging credentials but deny production credentials), independent of feature-level RBAC.. Permission control for Resources requires the Enterprise plan; per-environment override requires selecting 'Define specific resource access' on a resource.
Single sign-on (SSO)
Sim
Retool
Yes: Retool supports SAML 2.0 SSO (Business plan and above) compatible with Okta, Azure AD, Google Workspace, OneLogin and other SAML/OIDC providers, plus SCIM-based auto-provisioning (create/update/deactivate users automatically) available on Cloud or self-hosted 2.32.1+.. The Enterprise plan separately lists 'Custom SSO' as a feature, suggesting tiered SSO capability between Business and Enterprise.
Vetted first-party integrations
Sim
Yes: every one of Sim's 302 blocks is first-party authored and code-reviewed through the standard pull-request process in the main Sim repository; there is no public marketplace where an arbitrary third party can publish and have other users install executable tool code without going through Sim's own review. Custom code steps run inside Sim's own isolated-vm sandbox rather than as an installable third-party skill package, so the supply-chain trust boundary is Sim's codebase review, not an open registry.
Retool
Yes: Retool's built-in integrations (Resources) are a first-party catalog of roughly 50 databases, APIs, and cloud services built and maintained by Retool, not an open marketplace of third-party-submitted connectors. Retool separately offers Custom Component Libraries, which let a customer's own developers pull in npm packages to build custom UI components, but these are private to the authoring organization by default (or explicitly made public by that org), not a shared registry where other Retool customers install code published by unrelated third parties.. A custom component loads into a sandboxed iframe, and Retool's custom-component-guide plus a community forum thread ('Custom Component Vulnerabilities') flag that developers should run npm audit on dependencies pulled into their own component libraries. This is a supply-chain caution for self-authored code, not an incident involving a shared marketplace, since no public component marketplace exists.
PII redaction
Sim
Retool
No: Retool has no automated PII-detection or redaction system for workflow content or logs. The closest control is the manual, per-query 'Remove parameters from logs' option in Advanced Options, which lets a builder exclude specific named parameters (which could include PII) from being written to audit logs. This is manual exclusion, not automatic PII detection or redaction.
Custom data retention
Sim
Retool
No: Retool Cloud has a fixed one-year audit log retention with only the most recent three months browsable in the UI; there is no documented org-configurable retention window on Cloud. Self-hosted orgs manage retention themselves via their own infrastructure, but that is operator-managed, not a Retool-provided configurable setting.. No configurable retention windows exist for other resources, like soft-deleted items, either.
White-labeling
Sim
Retool
Yes: Retool's Enterprise plan includes full white-labeling, letting orgs replace the Retool logo/favicon and remove references to the Retool name across login pages, headers, invite/password-reset emails, and app presentation mode. The Business plan gets custom branding with fewer white-label controls. Separately, white-labeled Retool Mobile apps can be requested for the iOS/Android app stores.. Custom domain (Business/Enterprise) is required alongside white-labeling for a fully de-branded experience.
AI capabilities
Multi-LLM support
Sim
21 providers incl. OpenAI, Anthropic, Google, Bedrock21 provider integrations (OpenAI, Anthropic, Google/Gemini, Azure OpenAI, Azure Anthropic, Groq, Cerebras, Mistral, xAI, Bedrock, Vertex, Ollama, OpenRouter, and more). apps/sim/providers/models.ts defines 21 provider entries; openrouter/litellm/vllm/ollama resolve models dynamically at runtime rather than from a hardcoded model list.
Retool
OpenAI, Anthropic, Google, Bedrock, Azure, or BYO modelDirect providers OpenAI, Anthropic, and Google; cloud service providers AWS (Bedrock) and Azure (OpenAI); plus a "bring your own model" option.. Retool lists these categories without enumerating specific model versions.
Agent reasoning blocks
Sim
Natural-language building
Knowledge base / RAG
Sim
Retool
Yes: Retool Vectors is a Retool-managed vector database that stores and indexes text, PDF, or web-page content, so AI apps and agents can retrieve relevant context in one click. Embedding calls always go through OpenAI's API (default model text-embedding-ada-002), regardless of which chat model is used.
MCP support
Sim
Retool
Evaluation & guardrails
Sim
LLM-judge Evaluator plus Guardrails validation blockEvaluator block (LLM-judge scoring against user-defined named metrics) and Guardrails block (JSON validity, regex, RAG/hallucination scoring, PII detection/masking). These are per-call scoring/validation primitives, not a batch golden-dataset eval-suite runner or A/B prompt-testing harness.
Retool
Access/audit controls only, no eval frameworkPartial: Retool provides governance-style guardrails, enterprise access controls, monitoring, and audit trails for agent and workflow actions, but no dedicated evaluation or test-suite framework for validating AI output quality.. Retool's guardrails are access and observability controls (enterprise access controls, monitoring, and audit trails), not a dedicated evals product.
Human-in-the-loop
Sim
Retool
Yes: dedicated human-in-the-loop approval tasks distinct from a delay/wait step. Retool Agents and Workflows support an auditable, permissionable approval task that must be approved by one or more people in a designated permission group before a run proceeds (for example, reviewing an agent's proposed tool call or action). Approvers can be notified via Retool app/task assignment or Slack/email through workflow blocks. The run resumes automatically once the decision is recorded, and every step is logged to the audit trail.
Generative media
Sim
Retool
Image generation only, no video/TTS/STTNative image generation only. No native video generation, text-to-speech, or speech-to-text block.. Retool's AI query block includes a native "Generate image" action (model options such as dall-e-2/gpt-image-1 via OpenAI) that returns a base64-encoded PNG. There is no native video-generation, text-to-speech, or speech-to-text block; users build these via third-party APIs.
Dynamic tool use
Sim
No: an Agent block calls tools the workflow author explicitly added to it at build time, rather than browsing and picking from a broader pool (e.g. an entire MCP server catalog) at inference time. Runtime MCP "discovery" exists to resolve/refresh the schema of an already-configured tool. The model does not browse or choose from the server's full tool list.
Retool
Not publicly documentedUnknown. Not publicly documented.
Automatic model fallback
Sim
No: a failed or rate-limited LLM call is retried using Sim's own hosted API keys for the same model, rather than automatically switching to a different model or provider. A "fallback" comment in the provider layer refers to rotating among Sim's own hosted API keys for the same model, not switching models.
Retool
Not publicly documentedUnknown. Not publicly documented.
Agent skills
Sim
Yes: named, reusable "Agent Skills" (built on the open Agent Skills / SKILL.md format) that agents load on demand via progressive disclosure, editable in-app or imported from a SKILL.md file or GitHub URL. Only the skill name and description sit in the agent's system prompt (~50-100 tokens each); the full instructions load into context only when the agent calls load_skill.
Retool
Unknown, no shared skills-library feature foundUnknown: Retool has no feature for defining a reusable, named prompt or knowledge snippet once and reusing it across multiple agents by reference. Retool's agent docs describe per-agent instructions and system prompts, plus connecting Resources, Vectors, and MCP servers as tools, but not a shared 'skills library' construct.. Retool has reusable components and shared primitives for apps and workflows generally, but nothing matches a cross-agent named prompt-snippet system, the kind Anthropic and Replit call 'Agent Skills'.
Native chat deployment
Sim
Retool
Estimated yes, via Agent Chat component embedded in appsEstimated yes: Retool Agents include a chat interface for testing and interacting with an agent, and can be embedded into deployed Retool apps via an Agent Chat component, giving end users a conversational surface, alongside other deployment targets like email and workflows/API. A public 'share thread' replay link also exists for individual conversations.. Chat is delivered by embedding the Agent Chat component in a publicly-shared app rather than a single-click standalone public chat deployment; there is no dedicated one-click public chat endpoint.
Parallel execution
Sim
Yes: a native Parallel block fans a run out into concurrent branches (fixed count or one per list item) and joins their results back into the workflow automatically. Contained blocks run concurrently instead of sequentially, either a fixed number of times or once per item in a list/collection, and each branch's output aggregates for downstream blocks.
Retool
Yes: Retool Workflows has a Branch block that outputs to multiple downstream blocks, creating separate paths that run at the same time, and a Loop block with a dedicated parallel execution mode for concurrent iteration. A block with multiple incoming connections waits for all of them to finish before running, which is how parallel paths join back together. Some older community forum reports describe blocks executing sequentially rather than concurrently in certain cases, so real-world concurrency may vary from the documented behavior.. Official docs describe multi-output blocks and a Loop block parallel mode; a small number of community forum threads report inconsistent concurrent execution in practice.
Agent2Agent (A2A) protocol
Sim
Retool
Yes: Retool documents native Agent2Agent (A2A) protocol support for Retool-built agents, including agent cards, sending messages, polling for task updates, and streaming updates over Server-Sent Events. Support is ingress-only (external agents can call a Retool agent, not the reverse), limited to the HTTP+REST and JSON-RPC transports, and authenticates callers with an API key header rather than delegated auth.. Retool docs describe this as "the core set of A2A functionality" and explicitly note the input-required and auth-required task states are not supported, so tools requiring delegated authentication or approval will fail over A2A.
Loop / iteration block
Sim
Retool
Yes: a dedicated Loop block runs an embedded set of blocks once per item in an array, referencing each item and its index via value and index.. The Loop block supports Sequential mode (each iteration completes before the next starts, with an optional delay to avoid rate limits), Parallel mode (all iterations run simultaneously), and Batch mode (a configurable number of iterations run in parallel per batch, default batch size 10) before moving to the next batch.
Integrations
Integrations
Sim
302 blocks, ~3,900 tool actions302 first-party blocks, ~3,900 underlying tool actions. Sim's landing page cites "1,000+ integrations," a broader figure counting individual API actions rather than top-level blocks. Both numbers describe the same integration surface.
Retool
90+ connectors plus REST/GraphQL/gRPC90+ listed integrations/connectors on the public integrations page, plus generic REST API, GraphQL, and gRPC connectivity for anything without a native connector.. Categories include databases, cloud platforms, CRMs, messaging, and AI services (OpenAI, Anthropic, Google Gemini, etc.).
Trigger types
Sim
Webhook, cron, chat, REST API, triggers for 61 appsWebhook, schedule/cron, chat, REST API, and event-based triggers for 61 apps (Slack, Gmail, GitHub, Stripe, etc.)
Retool
Not publicly documentedUnknown. Not documented in a single consolidated reference.
Custom code steps
Retool
Not publicly documentedUnknown. Not publicly documented.
API publishing
Sim
Retool
Enterprise platform APIs plus MCP server accessEnterprise plan includes "platform APIs" for managing/orchestrating Retool resources; Retool itself can also be exposed as an MCP server for programmatic/agent access.. Platform APIs are an Enterprise-tier pricing feature. Retool has not published whether individual apps or workflows can be published as standalone REST endpoints.
SDKs & extensibility
Sim
Retool
Custom Component React/TS kit, no multi-language SDKCustom Component dev kit (React/TypeScript) + CLI, plus a community Custom Component Gallery; no general-purpose client SDK for multiple languages found. Retool provides a TypeScript API for building custom React components locally (using standard npm packages and Retool's `retool-ccl` CLI tool) that adds new properties and events to the app editor. Finished components can be published to the community Custom Component Gallery or shared privately as component libraries. There is no multi-language client SDK, such as Python, Node, or Go REST client libraries, beyond this TypeScript toolkit and workflow webhook/REST triggers.
Publish as MCP server
Sim
Retool
No, not in the sense of turning one specific app into its own callable tool: Retool's MCP server (public beta) exposes Retool's own build and management actions (create/edit apps, run queries, manage users, inspect resources) so external AI tools like Claude or Cursor can operate the Retool platform itself. It does not let you publish a single deployed app or workflow as its own standalone MCP tool for outside consumption.. Retool agents can call external MCP servers as tools, and Retool itself is an MCP server for managing the workspace, but no documentation confirms publishing an individual workflow or app as its own MCP endpoint for external tool-calling.
Observability & durability
Tracing & observability
Sim
Yes: execution logs include a per-block/per-span trace view (duration, cost, token counts, and latency stats like TTFT/TPS) with expandable nested iteration groups, plus a "View Snapshot" frozen copy of the workflow structure and block states at run time for debugging. This trace view is built directly into Sim rather than a raw export browsable in an external tool like Jaeger, and does not expose aggregate latency-percentile charts (p50/p95/p99). The run snapshot serves as a log-detail/debugging artifact rather than a resumable mid-run checkpoint.
Retool
Block-level run logs; tracing via Datadog/SentryPer-run/per-block execution logs and status in Run History; no native distributed tracing with spans. Latency percentile and error-rate dashboards require connecting Datadog or Sentry.. Run History lists every workflow run with date/time/status and lets you drill into each block to find where a failure occurred, filterable by error/success/info. This is block-level status logging, not distributed tracing with spans. For latency percentile or error-rate dashboards, Retool points to connecting an external tool like Datadog or Sentry rather than offering a built-in metrics dashboard.
Durability & retries
Sim
Tool-call retries (up to 10x); single-attempt job orchestrationIndividual tool/API calls have configurable exponential-backoff retry (up to 10 attempts). The background job-orchestration layer itself retries only once by design. Durability instead comes from consecutive-failure tracking on schedules and the human-in-the-loop snapshot pause/resume mechanism. Sim does not offer guaranteed-once-only block execution, a failed-run holding queue for manual recovery, or a "replay a past execution with its original inputs" feature. The per-execution debugging snapshot serves as a log-detail artifact rather than a resumable mid-run checkpoint.
Retool
Configurable retries with backoff; no checkpointingAutomatic retries with configurable schedules and exponential backoff. No durable checkpointing or one-click replay of a past execution with its original inputs.. Workflows can configure error handlers to automatically retry failed blocks on a schedule, including exponential backoff for rate-limited APIs/data sources, plus block-level and global error handlers for unhandled errors. There is no durable checkpointing of workflow state or one-click replay of a past execution with its original inputs beyond re-running/retrying.
Failure alerting
Sim
Retool
DIY via error handlers, no built-in alertingAlerting is DIY. Built via error-handler blocks wired to Slack/email/notification actions. No built-in proactive alert or cost/latency-threshold subscription system.. Retool Workflows exposes `workflowContext.currentRun.error` inside an error handler block, which builders commonly wire to a Slack or email notification action to be proactively notified of a failed run. There is no native cost/latency-threshold alerting feature (e.g., an admin setting an alert for runs exceeding a cost or duration threshold); this is typically DIY via error handlers.
Data drains
Sim
Yes: Enterprise orgs can continuously export workflow logs, job logs, or audit logs on a schedule to a customer-owned S3 bucket, GCS bucket, Azure Blob container, BigQuery table, Snowflake table, Datadog logs intake, or an HTTPS webhook. Each drain exports exactly one data source; multiple drains are created to export multiple sources. Viewing drain config/run history is restricted to org owners/admins.
Retool
Yes: Retool Enterprise orgs (Cloud or self-hosted 3.38 Edge+) can continuously stream audit log events to Datadog, and self-hosted deployments can set LOG_AUDIT_EVENTS=true to output all audit events to stdout for ingestion by any external log pipeline.. Cloud Business/Enterprise can also download audit logs from the UI (batch, not a live drain). No direct S3/BigQuery/generic-webhook drains are documented; Datadog and self-hosted stdout are the documented mechanisms.
Async execution
Sim
Yes: a workflow can be triggered in fire-and-forget async mode, returning HTTP 202 with a job ID immediately, then polled via a dedicated jobs endpoint through queued/processing/completed/failed states. Async jobs are tracked via polling the job endpoint rather than a completion webhook/callback option.
Retool
Yes: Retool Workflows can run asynchronously in the background. Triggering a workflow (via the API startTrigger endpoint or a webhook) kicks off a run that continues executing after the initial request returns, and you can check back on it later using the Retool API's Get Workflow Run Details endpoint, which returns the run's status and result.. Retool explicitly distinguishes 'synchronous workflow runs' (blocks until a Response block executes, 15-minute timeout) from 'asynchronous workflow runs' (up to 30 hours) in its own docs, and provides a Get Workflow Run Details API to fetch a run's status/result after triggering.
Execution limits
Sim
5-50 min sync timeout, 90 min async, 15-300 concurrentPlan-gated: synchronous API calls time out at 5 minutes on the free plan and 50 minutes on paid plans, async calls at 90 minutes on every plan, with 15 to 300 concurrent executions per billing entity depending on plan. These limits are not published in docs; request bodies are separately capped at 10 MB.
Retool
Yes: Retool publishes concrete execution limits. Synchronous workflow runs (blocking until the first webhook Response block) time out after 15 minutes; asynchronous runs time out after 30 hours, though workflows with a User Task or Wait block can run indefinitely (individual Wait blocks still cap at 60 days). Resource and query blocks can run up to 2 minutes in sync mode or up to 10 minutes in async mode (Cloud). Concurrency is capped at 50 in-flight outbound requests per workflow and 100 concurrent workflow runs on Retool Cloud, with a burst allowance of 200 runs in a 10-second window, and each run can use up to 2.5GB of memory.. Self-hosted customers can raise the 50 in-flight request cap via the WORKFLOW_REQUEST_CONCURRENCY_LIMIT env var, and memory enforcement (2,500 MB default) is opt-in via WORKFLOW_MONITOR_PROCESS_ENABLED.
Partial-failure handling
Sim
Retool
Yes: Retool Workflows let a failing block route to a dedicated error-handling path while the rest of the run continues, rather than always halting the whole execution. Each block has a red 'On Error' connector you can wire to a downstream handler block, and workflow-level (global) error handlers catch any unhandled errors from blocks that don't have their own On Error connection.. Global error handlers only fire for blocks lacking a block-level On Error connection, avoiding double handling; error details are exposed at workflowContext.currentRun.error for logging.
Support
Support channels
Sim
Community support plus Enterprise 'Dedicated Support'Community (open source, GitHub) plus an unquantified "Dedicated Support" flag on the Enterprise plan. Enterprise and pricing pages do not include CSM, onboarding/enablement, or professional-services details beyond a plan-comparison-table "Dedicated Support" flag.
Retool
Forum on free tier up to dedicated Enterprise supportCommunity Discourse forum (free tier), email + chat (Team plan), dedicated/priority support (Business and Enterprise plans); a Slack group is available to invited "Power Users.". Support channels scale with plan tier, from community forum access on the free tier up to dedicated support on Business and Enterprise.
SLA
Sim
Community
Sim
100,000+ buildersOver 100,000 builders use Sim
Retool
Active Discourse forum, no public star/member countCommunity Discourse forum with 1,000+ posts. No GitHub star count or Slack member count is publicly disclosed.. Forum activity figures come from third-party reporting rather than a published Retool metrics page.
Academy / training
Sim
Retool
Yes: Retool University (university.retool.com) is a structured education platform with course paths for developers, admins, and architects, including a Retool Platform Developer certification path with earnable digital badges, plus Labs walkthroughs and recorded Developer Day sessions.. Launched with five course paths; Retool Platform Developer and Platform Admin courses award Credly digital badges. A third-party Coursera course also exists but the primary academy is Retool University.
Sim standout features
AI Copilot / Chat agent-building surface
Chat and in-editor Copilot suggest and build workflow changes directly.
A natural-language surface (Chat) and in-editor Copilot that can explain, suggest, and build workflow changes directly, backed by a dedicated copilot module with its own tool registry.Hybrid semantic + keyword knowledge base
Combines vector and full-text search with configurable chunking across 11 file formats.
Built-in RAG with pgvector embeddings and a generated tsvector column for combined vector + full-text search, plus a token-based chunker with configurable chunk size/overlap and 11 supported file formats (csv, doc, docx, html, json, md, pdf, pptx, txt, xlsx, yaml).Native MCP client and server
Call external MCP servers as tools, or expose Sim workflows as an MCP server.
A dedicated MCP block lets any workflow call external MCP servers as a tool, and a serve/workflow-servers API surface lets Sim expose its own workflows as MCP servers.Fork a workspace into dev, qa, and prod environments
Fork, diff, and promote environments with mandatory credential remapping.
Fork a whole workspace into a dev/qa/prod-style child environment, preview a diff, and promote changes bidirectionally. Credential and env-var remapping is required on every promote, so secrets never cross environments silently.Human-in-the-loop approvals with durable resume
Pause a run for human approval and resume later via a durable snapshot link.
A dedicated block pauses a run and waits for a human-submitted approval form, backed by persisted execution snapshots so the run can resume later via a link, even after a server restart.Self-hostable under Apache 2.0
Fully open source with Docker Compose and Helm deployment options.
Fully open source (Apache 2.0), with Docker Compose files and a Helm chart for Kubernetes deployment, alongside a managed cloud-hosted option.Documented Retool limitations
Proprietary, closed-source core
Closed-source product; self-hosted still requires a Retool license key.
Retool is proprietary and closed-source. The self-hosted deployment can be forked and customized and bundles open-source dependencies, but still requires a Retool-issued license key to run. No OSS license covers the product itself.Docker self-hosted deployment explicitly not production-ready
Docker Compose setup is for testing only; production needs Kubernetes/Helm.
The Docker Compose self-hosted setup (bundled Postgres container, no SSL configured) is for local and non-production testing only. Production self-hosting requires a Kubernetes/Helm deployment.No dedicated built-in eval/guardrail framework documented
No dedicated evaluation or guardrail framework for AI output quality.
Retool documents governance controls (audit logs, RBAC, enterprise access controls) but no dedicated evaluation, testing, or guardrail framework for validating AI agent behavior or outputs before production use.Agents billed separately by the hour, outside the AI-credit pool
Agents usage is billed hourly, separate from the AI-credit pool.
Retool Agents usage is metered and billed hourly, separate from the monthly AI-credit allocation used for app-building and AI actions. This adds a second, less predictable usage-based cost on top of seat pricing.Bottom line
Choose Sim if you want an open-source, self-hostable AI workspace that treats AI agents as first-class citizens: native multi-LLM support, real-time multiplayer editing, environment promotion (dev/qa/prod), human-in-the-loop approvals, and enterprise governance (SSO, credential-level permissions, audit logs) built in rather than bolted on.
Choose Retool if you specifically need retool Vectors (managed vector store): A Retool-managed vector database that automatically indexes uploaded text, PDFs, or web pages, so AI apps and agents can look up relevant content with one click instead of building a custom search pipeline. The lookups always run through OpenAI's embedding API, even when the chat model is a different provider.
Frequently asked questions
Sim is an open-source AI workspace where teams build, deploy, and manage AI agents visually, conversationally, or with code. Retool is a low-code platform for building, deploying, and managing internal software (apps, workflows, and AI agents) that connect to databases, APIs, and LLMs. Teams considering a switch typically weigh licensing (Sim is Apache 2.0 and self-hostable), pricing model, and how AI-native the platform's agent-building experience is.