crw-mcp

The open-source alternative to Firecrawl. One static binary, ~50 MB RAM idle, a native fastCRW REST API under /v1/* (scrape, crawl, map, search, structured extraction, and change tracking), plus a /firecrawl/v2/* Firecrawl compatibility layer for migrations, batch scrape, and PDF parse. Self-host free under AGPL-3.0, or hit our managed API at api.fastcrw.com. Reproducible 63.74% truth-recall on the public 1,000-URL dataset (diagnose_3way.py, 2026-05-08) — see fastcrw.com/benchmarks. Built in Rust because every millisecond of agent latency compounds.

Works with: Claude Code · Cursor · Windsurf · Cline · Copilot · Continue.dev · Codex · Gemini CLI

Why fastCRW?

• Rust-native, single static binary — no Redis, no Node.js, no Python venv, no headless-browser sidecar in the request path. One binary, one config file, one process.

• ~50 MB RAM idle — leaves headroom on a $5 VPS. Browser-render-first stacks (Firecrawl, Crawl4AI) carry a Chromium heap baseline measured in hundreds of MB before a single request lands.

• Native /v1, compatibility /firecrawl/v2 — new fastCRW projects should use /v1/scrape, /v1/crawl, /v1/map, and /v1/search. Existing Firecrawl v2 SDK projects can use the /firecrawl/v2/* compatibility layer (FirecrawlApp(api_url="https://api.fastcrw.com")) and validate the documented differences before switching production traffic.

• Change tracking & monitoring — diff a page against a prior snapshot (markdown git-diff, per-field JSON, or both) with an optional LLM "meaningful-change" judge. Stateless changeTracking primitive in the engine; scheduled monitors + signed-webhook/email alerts on the managed platform. See the Monitoring docs.

• AGPL-3.0 open core + managed option — self-host free, or point at api.fastcrw.com for managed proxy network, dashboard, and SLA without the AGPL obligations on your application code.

Related MCP server: webpeel

Comparison Table

Qualitative positioning vs. the two most-cited alternatives — the same two in the reproducible benchmark below. Numerical claims trace to the inline sources noted; everything else is descriptive.

Pricing/spec cells where claimed link to the vendor page; everything else is the qualitative architectural shape, not a comparison number.

Quickstart

Hit the managed API at api.fastcrw.com, or self-host the same binary.

# /v1/scrape — URL → markdown / HTML / JSON / links
curl -X POST https://api.fastcrw.com/v1/scrape \
  -H "Authorization: Bearer $CRW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com","formats":["markdown"]}'

# /v1/scrape + formats:["json"] — structured JSON extraction via a JSON Schema
curl -X POST https://api.fastcrw.com/v1/scrape \
  -H "Authorization: Bearer $CRW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "url":"https://example.com",
    "formats":["json"],
    "jsonSchema":{
      "type":"object",
      "properties":{"title":{"type":"string"}}
    }
  }'

# /v1/crawl — async multi-page job (returns a job id; poll with /v1/crawl/:id)
curl -X POST https://api.fastcrw.com/v1/crawl \
  -H "Authorization: Bearer $CRW_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url":"https://docs.example.com","maxDepth":2,"maxPages":50}'

# Self-host (no auth, localhost) — single docker command
docker run -p 3000:3000 ghcr.io/us/crw
curl http://localhost:3000/v1/scrape \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com"}'

Other install paths (each documented under Install further down):

npx crw-mcp                           # zero install — runs the embedded engine
pip install crw                        # Python SDK (auto-downloads binary)
brew install us/crw/crw                # Homebrew
cargo install crw-cli                  # Cargo
curl -fsSL https://fastcrw.com/install | sh

Why Rust?

Cold start is sub-second and the resident memory ceiling is bounded by the crawl queue, not by a JavaScript runtime or a headless browser parked in the background. An agent that issues N scrapes per task pays the network floor N times — anything you add on top (process spawn, JIT warmup, browser navigation overhead) multiplies. Pushing the request-path language down to Rust strips that surcharge out of every call. The same property lets one static binary saturate a $5 VPS instead of needing a multi-container compose stack, which is why the idle footprint is in the tens of MB rather than the hundreds.

MCP + SDK quickstart

fastCRW ships a built-in MCP server so any MCP-compatible agent (Claude Code, Cursor, Windsurf, Cline, Continue.dev, Codex, Gemini CLI) can call scraping tools without bespoke glue. Embedded mode runs the engine in-process — no server, no API key, no setup. The crw Python SDK and the crw-mcp Node binary both shell to the same Rust core.

npm install -g crw-mcp          # MCP server (Node wrapper)
pip install crw                 # Python SDK (auto-downloads binary)
claude mcp add crw -- npx -y crw-mcp                                       # Claude Code, embedded
claude mcp add crw \
  -e CRW_API_URL=https://api.fastcrw.com -e CRW_API_KEY=… \
  -- npx -y crw-mcp                                                        # Claude Code, managed

Per-client config recipes (Claude Desktop, Cursor, Windsurf, Cline, Continue.dev) live under docs.fastcrw.com/mcp-clients/.

Agent Skills

Beyond raw MCP tools, fastCRW ships a set of agent skills — reusable instruction packs that teach AI coding agents when and how to scrape, crawl, map, search, parse, extract, and change-track the web. Install into any agent (Claude Code, Codex, Cursor, OpenCode, Gemini CLI, Windsurf + more) with one command:

npx skills add us/crw                 # all 12 skills, into every detected agent
npx skills add us/crw@crw-scrape      # just one
npx skills add -g us/crw              # global (user-level)

The skills drive the crw CLI, the crw-mcp tools, or the REST API — pick whatever surface you have. No API key needed for self-hosted search (SearXNG). Full catalog and per-skill docs: skills/. Also packaged as a plugin marketplace for Claude Code, Codex, and Cursor (.claude-plugin/, .codex-plugin/, .cursor-plugin/).

Self-host vs Managed

The binary is the same in both modes — you can develop against your self-hosted instance and ship to managed without code changes.

Install

MCP server (crw-mcp) — recommended for AI agents

npx crw-mcp                              # zero install (npm)
pip install crw                          # Python SDK (auto-downloads binary)
brew install us/crw/crw-mcp              # Homebrew
cargo install crw-mcp                    # Cargo (full embedded, ~17 MB)
docker run -i ghcr.io/us/crw crw-mcp     # Docker

Lean browser-free proxy build (~4.2 MB, no headless browser engine — proxy/cloud mode only):

cargo build --profile release-small --no-default-features -p crw-mcp

CLI (crw) — scrape URLs from your terminal

brew install us/crw/crw

# One-line install (auto-detects OS & arch):
curl -fsSL https://fastcrw.com/install | CRW_BINARY=crw sh

# APT (Debian/Ubuntu):
curl -fsSL https://apt.fastcrw.com/gpg.key | sudo gpg --dearmor -o /usr/share/keyrings/crw.gpg
echo "deb [signed-by=/usr/share/keyrings/crw.gpg] https://apt.fastcrw.com stable main" \
  | sudo tee /etc/apt/sources.list.d/crw.list
sudo apt update && sudo apt install crw

cargo install crw-cli

API server (crw-server) — native REST API plus Firecrawl compatibility

For serving multiple apps, other languages (Node.js, Go, Java), or as a shared microservice.

brew install us/crw/crw-server

# One-line install:
curl -fsSL https://fastcrw.com/install | CRW_BINARY=crw-server sh

# Docker:
docker run -p 3000:3000 ghcr.io/us/crw

Docker Compose ships with lightpanda by default; chrome is opt-in:

docker compose up -d                                         # http + lightpanda
docker compose --profile heavy up -d                         # + chrome failover
docker compose -f docker-compose.yml \
  -f docker-compose.stealth.yml --profile stealth up -d      # browserless stealth tier

There's also an optional Camoufox stealth tier (REST sidecar, opt-in) for fingerprint-blocked targets the CDP renderers can't pass — off by default and never touches the auto chain unless you turn it on. Build with --features camoufox; see JS rendering → Camoufox.

See the self-hosting guide for production hardening, auth, reverse proxy, and resource tuning.

API endpoints

Firecrawl v2 compatibility surface — scrape, crawl, map, and search are also served under /firecrawl/v2/* with Firecrawl v2 request/response shapes, plus compatibility-only POST /firecrawl/v2/batch/scrape, POST /firecrawl/v2/parse (PDF → markdown), and GET /firecrawl/v2/crawl/active. Use this when migrating existing Firecrawl v2 SDK code; new fastCRW integrations should start with /v1.

Full reference at docs.fastcrw.com/#rest-api. The Firecrawl compatibility matrix (field-by-field diff) lives in COMPATIBILITY-firecrawl.md.

Benchmark

Reproduce it yourself first — the canonical harness is diagnose_3way.py (matches truth text against md + strip_md_links(md), applied identically to all three tools — a fairness control, not a looser number):

cd ~/coding/crw/crw-opencore
docker compose -f docker-compose.yml -f docker-compose.override.yml \
               -f docker-compose.stealth.yml --profile stealth up -d
docker start crawl4ai-bench
cd ~/coding/crw/competitors/firecrawl && docker compose up -d

cd ~/coding/crw/crw-opencore
uv run python bench/diagnose_3way.py \
  --max-urls 1000 --tools crw,crawl4ai,firecrawl \
  --concurrency 5 --timeout 120 \
  --out bench/server-runs/diag3w-1000-full.jsonl

3-way scrape benchmark, full 1,000-URL run on Firecrawl's scrape-content-dataset-v1 (diagnose_3way.py, 2026-05-08, concurrency 5, timeout 120s):

fastCRW leads on every axis — top truth-recall, fastest median, and the lowest p90 tail — with 0 thrown errors across all 3,000 requests, and it uniquely recovers 34 URLs the other two miss (70% more than crawl4ai and Firecrawl combined). The 63.74% denominator is 819 labeled/matchable URLs, not 3,000 requests, not 1,000.

Two tunable modes, one engine, one config toggle. Recall mode (the full ladder) maximizes truth-recall, recovering the long tail of hard pages the others miss. Fast mode (LightPanda-only, no Chrome tier) optimizes the latency tail — p90 4348 ms, the lowest of the three (diagnose_3way.py, N=1000). Same binary, same API; pick accuracy or latency per workload.

Full result of record: bench/server-runs/RESULT_3WAY_1000_FULL.md.

SDKs and integrations

Python

pip install crw

from crw import CrwClient

# Managed (includes web search):
client = CrwClient(api_url="https://api.fastcrw.com", api_key="YOUR_API_KEY")
# Local (embedded, no server needed):
# client = CrwClient()

result = client.scrape("https://example.com", formats=["markdown", "links"])
pages = client.crawl("https://docs.example.com", max_depth=2, max_pages=50)
urls = client.map("https://example.com")
results = client.search("AI news", limit=10, sources=["web", "news"])

Requires Python 3.10+. Local mode auto-downloads crw-mcp on first use.

Framework extras:

pip install crw[crewai]    # CRW scraping tools for CrewAI agents
pip install crw[langchain] # CRW document loader for LangChain

TypeScript / Node.js

npm install crw-sdk

SDK examples →

Frameworks & platforms

CrewAI · LangChain · Agno · Dify · n8n · Flowise

All integrations →

Architecture

┌─────────────────────────────────────────────┐
│                 crw-server                  │
│         Axum HTTP API + Auth + MCP          │
├──────────┬──────────┬───────────────────────┤
│ crw-crawl│crw-extract│    crw-renderer      │
│ BFS crawl│ HTML→MD   │  HTTP + CDP(WS)      │
│ robots   │ LLM/JSON  │  LightPanda/Chrome   │
│ sitemap  │ clean/read│  auto-detect SPA     │
├──────────┴──────────┴───────────────────────┤
│                 crw-core                    │
│        Types, Config, Errors                │
└─────────────────────────────────────────────┘

Full architecture docs →

Security

• SSRF protection — blocks loopback, private IPs, cloud metadata (169.254.x.x), IPv6 mapped addresses, and non-HTTP schemes (file://, data:)

• Auth — optional Bearer token with constant-time comparison

• robots.txt — RFC 9309 compliant with wildcard patterns

• Rate limiting — token-bucket algorithm, returns 429 with error_code

• Resource limits — max body 1 MB, max crawl depth 10, max pages 1,000

Full security docs →

Contributing

Contributions are welcome — issues and PRs both.

1. Fork the repository

2. Install pre-commit hooks: make hooks

3. Create your feature branch (git checkout -b feat/my-feature)

4. Commit your changes (git commit -m 'feat: add my feature')

5. Push to the branch (git push origin feat/my-feature)

6. Open a Pull Request

The pre-commit hook runs the same checks as CI (cargo fmt, cargo clippy, cargo test). Run manually with make check.

Contributors

License

fastCRW is open source under AGPL-3.0. If you embed fastCRW in a closed-source product or expose it as a hosted service to third parties and you can't comply with AGPL's source-availability requirements, the managed offering at fastcrw.com includes a commercial carve-out, and standalone commercial licenses are available on request — write to hello@fastcrw.com.

Links

• Documentation: docs.fastcrw.com

• API reference: docs.fastcrw.com/#rest-api

• MCP setup guide: docs.fastcrw.com/#mcp

• Playground: docs.fastcrw.com/playground/

• Benchmarks: fastcrw.com/benchmarks

• Marketing site: fastcrw.com

• Changelog: CHANGELOG.md

• X / Twitter: @fast_crw

• LinkedIn: fastcrw

• Discord: discord.gg/kkFh2SC8

• MCP Registry: registry.modelcontextprotocol.io

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