Source: https://seerepo.com/r/simstudioai/sim/built Markdown source: https://seerepo.com/r/simstudioai/sim/built.md Description: sim is a TypeScript repo built with Next.js, React, and FastAPI. It stores its data in Postgres and MongoDB and takes payments with Stripe. # What is sim built with? sim is a TypeScript repo built with Next.js, React, and FastAPI. It stores its data in Postgres and MongoDB, takes payments with Stripe, sends email with Resend, stores files in AWS S3, uses AI through OpenAI and Anthropic, measures its use with PostHog, and uses Redis and MCP. It has 10,948 files and 4,073,540 written lines, with 3,682 test files. Read on November 2, 2026, at commit df7709b. Repository: https://github.com/simstudioai/sim ## Frontend ### The base - **[Next.js](https://seerepo.com/uses/nextjs)** - **[React](https://seerepo.com/uses/react)** ## Backend ### The base - **[FastAPI](https://seerepo.com/uses/fastapi)** ### Data - **[Postgres](https://seerepo.com/uses/postgres)**: 92 files · [apps/realtime/src/database/operations.ts, line 44](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/realtime/src/database/operations.ts#L44) - **[Redis](https://seerepo.com/uses/redis)**: 19 files · [apps/realtime/src/config/socket.ts, line 4](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/realtime/src/config/socket.ts#L4) - **[MongoDB](https://seerepo.com/uses/mongodb)**: 3 files · [apps/sim/lib/internal/mongodb/client.ts, line 1](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/lib/internal/mongodb/client.ts#L1) ### Services - **[PostHog](https://seerepo.com/uses/posthog)**: 20 files · [apps/sim/app/(auth)/signup/signup-form.tsx, line 7](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/app/(auth)/signup/signup-form.tsx#L7) - **[MCP](https://seerepo.com/uses/mcp)**: 19 files · [apps/sim/app/api/mcp/oauth/start/route.ts, line 1](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/app/api/mcp/oauth/start/route.ts#L1) - **[OpenAI](https://seerepo.com/uses/openai)**: 13 files · [apps/sim/providers/azure-openai/index.ts, line 4](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/providers/azure-openai/index.ts#L4) - **[Anthropic](https://seerepo.com/uses/anthropic)**: 5 files · [apps/sim/providers/anthropic/index.ts, line 1](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/providers/anthropic/index.ts#L1) - **[Stripe](https://seerepo.com/uses/stripe)**: 3 files · [apps/sim/lib/auth/auth.ts, line 29](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/lib/auth/auth.ts#L29) - **[AWS S3](https://seerepo.com/uses/aws-s3)**: 2 files · [apps/sim/lib/internal/s3/client.ts, line 1](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/lib/internal/s3/client.ts#L1) - **[Resend](https://seerepo.com/uses/resend)**: 1 file · [apps/sim/lib/messaging/email/providers/resend.ts, line 1](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/lib/messaging/email/providers/resend.ts#L1) ## Other repos with a similar stack - [langfuse/langfuse](https://seerepo.com/r/langfuse/langfuse/built): Next.js, React, Postgres, Redis, PostHog, MCP, OpenAI, Anthropic, Stripe, AWS S3 · [Compare](https://seerepo.com/compare/langfuse/langfuse/vs/simstudioai/sim) - [Significant-Gravitas/AutoGPT](https://seerepo.com/r/Significant-Gravitas/AutoGPT/built): Next.js, React, FastAPI, Postgres, Redis, PostHog, OpenAI, Anthropic, Stripe · [Compare](https://seerepo.com/compare/Significant-Gravitas/AutoGPT/vs/simstudioai/sim) - [lobehub/lobehub](https://seerepo.com/r/lobehub/lobehub/built): Next.js, React, Postgres, Redis, MCP, OpenAI, Anthropic, Resend · [Compare](https://seerepo.com/compare/lobehub/lobehub/vs/simstudioai/sim) - [mem0ai/mem0](https://seerepo.com/r/mem0ai/mem0/built): FastAPI, Postgres, Redis, MongoDB, PostHog, OpenAI, Anthropic, AWS S3 · [Compare](https://seerepo.com/compare/mem0ai/mem0/vs/simstudioai/sim) - [gitroomhq/postiz-app](https://seerepo.com/r/gitroomhq/postiz-app/built): Next.js, React, Postgres, Redis, MCP, OpenAI, Stripe, Resend · [Compare](https://seerepo.com/compare/gitroomhq/postiz-app/vs/simstudioai/sim) - [Dokploy/dokploy](https://seerepo.com/r/Dokploy/dokploy/built): Next.js, React, Postgres, PostHog, OpenAI, Anthropic, Stripe, Resend · [Compare](https://seerepo.com/compare/Dokploy/dokploy/vs/simstudioai/sim) ## Frequently asked questions ### What language is sim written in? sim is written in TypeScript: 10,948 files and 4,073,540 written lines. ### What framework does sim use? sim is built with Next.js, React, and FastAPI. ### What database does sim use? sim stores its data in Postgres and MongoDB. The proof: [apps/realtime/src/database/operations.ts, line 44](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/realtime/src/database/operations.ts#L44) ### What does sim take payments with? sim takes payments with Stripe. The proof: [apps/sim/lib/auth/auth.ts, line 29](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/lib/auth/auth.ts#L29) ### Does sim use AI? Yes. sim uses AI through OpenAI and Anthropic. The proof: [apps/sim/providers/azure-openai/index.ts, line 4](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/providers/azure-openai/index.ts#L4) ### What services does sim use? sim sends email with Resend, stores files in AWS S3, measures its use with PostHog, and uses Redis and MCP. The proof: [apps/sim/lib/messaging/email/providers/resend.ts, line 1](https://github.com/simstudioai/sim/blob/df7709bf5be6a42d51c5289364b98d32c4d38240/apps/sim/lib/messaging/email/providers/resend.ts#L1) ### Does sim have tests? Yes. sim has 3,682 test files. ### Which repos have a stack like sim's? The ones that share most of its stack: langfuse/langfuse, Significant-Gravitas/AutoGPT, and lobehub/lobehub. ## What is your repo built with? Any public repo, with no account: https://seerepo.com/r/owner/repo/built, with the owner and name it has on GitHub.