# AI tools for developers — pair-programming for any language.

> Def Code is a repo-aware AI CLI with Plan, Build, Design, and Test modes. Open-source Python SDK, MCP server, and a unified REST + streaming API across 50+ models. Works in any language; first-class TS/Python/Go/Rust/Swift/Kotlin.

## How Definable ships this

Multi-agent workflow. The Builder agent reads the prompt and plans the steps. The Executor runs each step across the user's connected apps. The Verifier checks every output and self-heals failed steps — rate limits, schema drift, off-brand responses — automatically.

## The problem

AI coding tools are siloed. Cursor only edits in its own editor. ChatGPT loses your repo context between messages. Most agents are demos that fall apart on a real codebase. And nobody gives developers a programmable API for the AI capabilities they actually need.

## How Definable solves it

Def Code is a CLI you can pipe anywhere — terminal, CI, scripts. It reads your repo, respects your toolchain, runs your tests. Four modes for four stages of work: Plan (scope before coding), Build (reviewable diffs), Design (UI scaffolding from a brief), Test (coverage for legacy code).

Underneath, Definable exposes everything as APIs. Unified REST + streaming across 50+ models. Open-source Python SDK for building agents and tools. MCP server so Definable's integrations and knowledge bases become tools for any MCP-compatible client — Claude Desktop, Cursor, Windsurf, custom agents.

Bring-your-own keys (OpenAI, Anthropic, Google, Cohere, Together, Groq, Azure OpenAI, AWS Bedrock) on Pro and above. Air-gapped and VPC deployments on Enterprise.

## Steps

1. **Install Def Code** — Single binary or npm install. Works on macOS, Linux, Windows.
2. **Point it at a repo** — Def Code indexes your codebase and respects your toolchain.
3. **Pick a mode and a prompt** — Plan for design decisions, Build for diffs, Design for UI, Test for coverage.
4. **Review and ship** — Output is reviewable diffs and PR-ready commits. Your toolchain stays your toolchain.

## Tools used

- [Def Code (CLI)](https://definable.ai/code/)
- [Compare to Cursor](https://definable.ai/compare/definable-vs-cursor/)

## Frequently asked questions

### What languages does Def Code support?

Any language your repo uses. First-class support for TypeScript, Python, Go, Rust, Swift, Kotlin. Working support for Ruby, Java, C#, PHP, C/C++, shell.

### Can I use my own API keys?

Yes on Pro and above — bring your own OpenAI, Anthropic, Google, Cohere, Together, Groq, Azure OpenAI, or AWS Bedrock keys.

### Is there an MCP server?

Yes. Definable exposes its integrations and knowledge bases as MCP tools, consumable from Claude Desktop, Cursor, Windsurf, or any MCP client.

## Related use cases

- [Build a company knowledge base your team can actually search.](https://definable.ai/use-cases/build-company-knowledge-base/)
- [AI document analysis with citations on every answer.](https://definable.ai/use-cases/ai-document-analysis/)

## Related

- HTML page: https://definable.ai/use-cases/ai-for-developers/
- Use-cases index: https://definable.ai/use-cases/
- Workflow: https://definable.ai/workflow/
- llms.txt index: https://definable.ai/llms.txt