Weftmap

🌐 Language:English · Español

Paste code, get an interactive call graph to understand what it does — across multiple languages, powered by Tree-sitter.

Weftmap turns source code into a navigable diagram of which functions call which. The differentiator is a pluggable, multi-language architecture: the backend adapts the analysis per language, and adding a new one takes only a few lines. No existing free tool does this well across several languages at once.

Status: MVP. Supports Python, JavaScript/TypeScript, Go, Rust and SQL. Diagram types: call graph (functions as nodes, calls as arrows) and, for SQL, entity-relationship (tables as nodes, foreign keys as edges).

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Table of Contents

• Features
• How it works
• Tech stack
• Getting started
• Available scripts
• Adding a language
• Project structure
• Roadmap
• Contributing
• License

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Features

• Multi-language — one parsing engine (Tree-sitter) for every language.
• Pluggable — a language is a single LangSpec + two Tree-sitter queries.
• Interactive diagram — pan, zoom and drag nodes (React Flow + dagre layout).
• Internal call graph — shows calls between functions defined in your code; calls to builtins/libraries are filtered out to keep the graph meaningful.
• No build step for the user — paste a snippet and hit Analyze.

How it works

┌──────────┐ POST /api/analyze ┌─────────────────────┐ Graph JSON ┌─────────────┐
│ Browser │ ────────────────────▶ │ Tree-sitter (WASM) │ ─────────────▶ │ React Flow │
│ (textarea)│ { code, language } │ per-language module │ {nodes,edges} │ (dagre) │
└──────────┘ └─────────────────────┘ └─────────────┘

1. You paste code and pick a language.
2. The backend (src/app/api/analyze/route.ts) validates the input, parses the code with the matching Tree-sitter grammar, and walks the syntax tree to build a normalized graph { nodes, edges }.
3. The frontend lays it out with dagre and renders it interactively with React Flow.

The call graph is extracted with declarative Tree-sitter queries (one for function definitions, one for calls) instead of hand-walking the AST — less code, easier to maintain, and the same approach works for every language.

Tech stack

Layer	Choice	Why
Framework	Next.js (App Router)	Frontend + backend in one project and one deploy
Language	TypeScript	Type safety across the whole stack
Parsing	Tree-sitter via web-tree-sitter (WASM)	One API for ~40 languages
Grammars	tree-sitter-wasms	Prebuilt grammar binaries
Diagram	React Flow + dagre	Interactive nodes, hierarchical layout
Tests	Vitest	Fast unit tests for the analyzers
Package manager	pnpm	Fast, disk-efficient installs

Getting started

Requirements: Node 20+ and pnpm.

# 1. Install dependencies
pnpm install
# 2. Start the dev server
pnpm dev
# open http://localhost:3000

Paste a snippet, choose python or javascript, and click Analyze.

Available scripts

Command	What it does
pnpm dev	Start the development server
pnpm build	Production build
pnpm start	Run the production build
pnpm test	Run the analyzer tests (Vitest)
pnpm typecheck	Type-check with tsc --noEmit
pnpm lint	Lint with ESLint

Adding a language

This is the most valuable kind of contribution. The architecture is pluggable: the backend adapts the analysis per language, and nothing else needs to change.

1. Add the grammar. Copy tree-sitter-<lang>.wasm into public/wasm/ (available from the tree-sitter-wasms package).
2. Create the analyzer. Add src/lib/analysis/analyzers/<lang>.ts with a LangSpec — two Tree-sitter queries (function definitions and calls) plus the set of node types that count as a function scope. Use python.ts as a template.
3. Register it. Add one line to src/lib/analysis/registry.ts.
4. Add the UI option. Add the language key to the LANGUAGES array in src/app/page.tsx.
5. Add a test. Drop a snippet → expected nodes/edges check in src/lib/analysis/analyzers/.

That's it.

Project structure

src/
app/
page.tsx # UI: textarea + language selector + diagram
api/analyze/route.ts # backend: validates input, calls the analyzer
components/
CodeInput.tsx # textarea + selector + analyze button
Diagram.tsx # React Flow + dagre rendering
lib/analysis/
types.ts # Graph + LanguageAnalyzer contract
registry.ts # language registry (the only file that knows them all)
treesitter.ts # loads/caches the Tree-sitter runtime + grammars
analyzers/
shared.ts # common call-graph extraction logic
python.ts # Python LangSpec
javascript.ts # JS/TS LangSpec
analyzers.test.ts # analyzer tests
public/wasm/ # Tree-sitter runtime + grammar .wasm files

Roadmap

Got an idea? Open an issue. Newcomer-friendly tasks are tagged good first issue.

Shipped

• Call graph for Python, JavaScript, TypeScript, Go and Rust
• SQL schema diagrams (ER / UML): tables, columns, PK/FK, relationships
• Pluggable per-language architecture (add a language in a few lines)
• Bilingual UI (en/es) with in-app docs

Next — help wanted

• More languages: Ruby (#13), Java (#14)
• Drive the Hero language chips from the registry (#15)
• Broaden analyzer test coverage (#16)
• Richer empty state when no functions are found (#17)

Later

• Project mode: analyze a whole folder as a single graph
• Node interaction: click to highlight callers/callees, function detail panel
• More diagram types: control-flow and module-dependency graphs
• Export the graph (PNG/SVG) and shareable permalinks
• More input methods: ZIP upload and GitHub repo URL
• Performance for large codebases

Contributing

Contributions are welcome — especially new languages. Please read CONTRIBUTING.md and our Code of Conduct.

Quick rules: main is protected (open a PR, CI must pass, one review required), and commits follow Conventional Commits.

License

MIT © DataDave-Dev