Ask questions about your codebase. Free Sourcegraph alternative.

Looking for a free open-source alternative to Sourcegraph? Lexithm indexes your repository and lets you ask questions about it in plain English. It extracts symbols, builds dependency graphs, and detects API routes — no CLI, no setup, no cost. Every answer cites the files it references.

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lexithm chatterminal
> You: where is auth handled
> scanning...
Auth is handled in src/auth/login.tsx — that file manages the login form and token exchange. It handles credential validation, session creation, and JWT token issuance.
Route protection is at src/middleware.ts — it checks for valid tokens on every request and redirects unauthenticated users to /login.
The token exchange endpoint lives at src/api/auth/route.ts — it handles OAuth callbacks, refresh token rotation, and returns the authenticated user session.
Capabilities

The best free Sourcegraph alternative for AI-powered code understanding. These capabilities are built and working today. Each one depends on the 16-stage indexing pipeline that runs when you import a repository.

Deep Code Indexing

AST-based parsing for Python, JavaScript, TypeScript, Go, Java, and Rust. Extracts symbols, call graphs, import graphs, API routes, database models, and architecture layers.

Conversational Q&A

Ask questions about your codebase in natural language. Responses cite the exact file paths and line numbers from your indexed repository.

Dependency Graphs

Bidirectional import and call graphs built during indexing. See what depends on a module and what it depends on.

API Route Detection

Automatically detects routes from FastAPI, Flask, Express, NestJS, Django, Gin, and Spring Boot applications.

Semantic Search

Find code by meaning, not just keywords. Every chunk is converted to embeddings for similarity-based retrieval across the entire repository.

How it works

Sign in with GitHub, pick a repository, and wait for indexing to finish. Once it's done you can ask questions about any part of your codebase.

  1. 1.Connect GitHub.Sign in with GitHub OAuth. No CLI, no config files, no manual setup.
  2. 2.Import a repository.Select a repo from your GitHub account. We clone it and start indexing automatically.
  3. 3.Wait for indexing.We parse every file, extract symbols, build dependency graphs, detect API routes, and scan for security issues. Most repos finish in a few minutes.
  4. 4.Ask questions.Type any question about your codebase. The LLM responds with cited file paths and line numbers from the indexed data.
Frequently asked questions
How is it different from just using ChatGPT?
└It reads your entire codebase — every file, every function, every import. ChatGPT only sees what you paste. This tool understands how all the pieces connect, so answers are specific to your actual code, not generic advice.
Can I use it to understand a project I just joined?
└That is one of the main use cases. You can ask high-level questions like "what does this project do" or dig into specific areas like "how does authentication work." It explains everything in plain English.
Does it check the entire codebase or just what I ask about?
└It indexes your whole repository first. When you ask a question, it searches the full index to find the most relevant parts and answers based on your actual code.
Do I need to install anything?
└No. Everything runs through your browser. Sign in with GitHub, pick a repository, and start asking questions. There is no CLI tool, plugin, or local setup required.
Is my code safe? Do you store it?
└Your repository is indexed on our backend, not stored by any LLM provider. Only the relevant code context is sent to generate each answer. You can delete the index or revoke GitHub access at any time.
How long does indexing take?
└Most repositories finish in 2-5 minutes. Larger projects with over 100,000 files can take up to 20 minutes. The progress screen shows each stage so you know exactly what is happening.
How is Lexithm different from Sourcegraph?
└Lexithm is a free open-source alternative to Sourcegraph focused on AI-powered code understanding. Unlike Sourcegraph which is built for enterprise code search at scale, Lexithm is free, requires no self-hosting or setup, and prioritizes natural language Q&A over regex search. You sign in with GitHub and start asking questions immediately — there is no CLI, no configuration, and no usage limits for code queries.

Try the free Sourcegraph alternative

Sign in with GitHub, import a repository, and start asking questions. No CLI, no setup, no cost.

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