fastCRW

Self-hosted, Rust-native web crawler & scraper for AI agents

The open-source alternative to Firecrawl. One static binary, ~50 MB RAM idle, Firecrawl-compatible REST API on both /v1/* and /v2/* (scrape, crawl, map, search, extract, plus v2 batch & parse) — a drop-in for the official Firecrawl SDKs — plus first-class MCP. 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

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_{Firecrawl's own 1,000-URL public dataset (diagnose_3way.py) — fastCRW leads on truth-recall, median latency, and fast-mode p90. Full numbers and one-command repro ↓}

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.
• Firecrawl-compatible drop-in — both the /v1/* and /v2/* surfaces (scrape, crawl, map, search, extract; plus v2-only batch & parse) with compatible request/response shapes. The v2 API is a drop-in for the official firecrawl-py v4 SDK (FirecrawlApp(api_url="https://api.fastcrw.com")) — swap the base URL and keep your code.
• 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.

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Comparison Table

Qualitative positioning vs. the three most-cited alternatives. Numerical claims trace to the inline sources noted; everything else is descriptive.

	fastCRW	Firecrawl	Crawl4AI	Spider
Language	Rust	Node.js + Playwright	Python + Playwright	Rust
License	AGPL-3.0 (commercial avail.)	AGPL-3.0 (commercial avail.)	Apache-2.0	Source-available / commercial (spider.cloud)
Self-host install size	Single static binary (~8 MB)	Multi-container (~500 MB+ image)	~2 GB image (browser bundled)	Managed-first; self-host via crate
Memory baseline (idle)	~50 MB	Large (Chromium heap)	Large (Chromium heap)	Light (Rust)
Firecrawl-compat API	Yes — v1 + v2 (/v1/* and /v2/*)	Native	No	No
MCP server	Built-in (crw-mcp)	Separate package	Community add-on	No first-party
Hosted option	api.fastcrw.com (BYOK or managed)	firecrawl.dev	None official	spider.cloud (primary product)
Reproducible public benchmark	Yes — 63.74% truth-recall on 1,000-URL dataset (diagnose_3way.py, 2026-05-08)	Vendor-published only	Vendor-published only	Vendor-published only

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

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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

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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.

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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/.

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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)

Tier	Skills
Core / verb ladder	crw (hub) · crw-search · crw-scrape · crw-map · crw-crawl · crw-parse · crw-extract · crw-watch
Quality / meta	crw-dynamic-search (context-isolating filter — the biggest token-saver) · crw-best-practices
Migration / ops	crw-migrate (one-line Firecrawl base_url swap) · crw-self-host

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/).

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Self-host vs Managed

	Self-host (free)	Managed — api.fastcrw.com
Best when	You want full data residency, AGPL is fine, you can run your own proxy strategy, latency to your infra matters more than ours.	You want zero infra, a global proxy network, a dashboard, usage metering, and AGPL carve-out for closed-source product code.
Install	docker run -p 3000:3000 ghcr.io/us/crw or cargo install crw-server.	Sign up at fastcrw.com — 500 free credits, no card.
Search	Bundled SearXNG sidecar (docker compose up).	Managed search backend.
Proxy rotation	Bring your own pool (proxy_list + proxy_rotation: round_robin / random / sticky_per_host) — rotated across the HTTP and JS/Chrome paths for scrape, crawl, and map; per-request BYOP supported. LightPanda can't proxy, so it's skipped (fail-closed) when a proxy is active.	Managed proxy network.
Cost	$0 + your hosting bill.	From $13/mo; pricing on fastcrw.com/pricing.
License obligations	AGPL-3.0 applies if you expose the API to third parties.	AGPL carve-out included.

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

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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) — Firecrawl-compatible REST API

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.

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API endpoints

Method	Endpoint	Description
POST	/v1/scrape	Scrape a single URL, optionally with LLM extraction or summary
POST	/v1/crawl	Start async BFS crawl (returns job ID)
GET	/v1/crawl/:id	Check crawl status and retrieve results
DELETE	/v1/crawl/:id	Cancel a running crawl job
POST	/v1/map	Discover all URLs on a site
POST	/v1/search	Web search via SearXNG sidecar, with optional content scraping
POST	/v1/change-tracking/diff	Diff a scrape against a supplied snapshot (the monitoring primitive) — single or batch
GET	/health	Health check (no auth required)
POST	/mcp	Streamable HTTP MCP transport

Firecrawl v2 surface — scrape, crawl, map, search are also served under /v2/* with Firecrawl v2 request/response shapes, plus v2-only POST /v2/batch/scrape, POST /v2/parse (PDF/doc → markdown), and GET /v2/crawl/active. This makes the official firecrawl-py v4 SDK a drop-in: FirecrawlApp(api_url="https://api.fastcrw.com").

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

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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):

Metric	fastCRW	crawl4ai	Firecrawl
Truth-recall (522/819 labeled URLs) recall mode	63.74%	59.95%	56.04%
p50 latency	1914 ms	1916 ms	2305 ms
p90 latency fast mode	4348 ms	4754 ms	6937 ms
Thrown errors (3,000 requests)	0	0	0

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.

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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 →

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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                │
└─────────────────────────────────────────────┘

Crate	Description
crw-core	Core types, config, and error handling
crw-renderer	HTTP + CDP browser rendering engine
crw-extract	HTML → markdown/plaintext extraction
crw-crawl	Async BFS crawler with robots.txt & sitemap
crw-server	Axum API server (Firecrawl-compatible)
crw-mcp	MCP stdio server (embedded + proxy mode)
crw-cli	Standalone CLI (crw binary, no server)

Full architecture docs →

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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 →

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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

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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.

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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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Star History

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