The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the Webcap listing page.
Screenshot any URL, extract structured data, monitor pages for changes — all via a single HTTP API call. Pay-per-call with no accounts, no API keys.
Pricing: $0.001/screenshot · $0.01/extraction batch · No subscriptions, no minimums.
| Feature | webcap | Screenshot APIs (typical) |
|---|---|---|
| Price | $0.001/screenshot | $0.01–0.10/screenshot |
| Accounts required | No | Yes |
| API keys | No | Yes |
| Payment | Card (Stripe) or crypto (USDC) | Credit card only |
| Batch support | Up to 50 URLs per payment | Limited |
| Self-hostable | Yes (Docker) | No |
| Open source | Yes (MIT) | No |
| Endpoint | What you get | Price |
|---|---|---|
POST /v1/x402/capture | Screenshot as PNG/JPEG/PDF (base64) + persistent public artifact link + OG metadata | $0.001 |
POST /v1/x402/extract | Structured page data as JSON: title, description, headings, paragraphs, links, images, word count, markdown. Batch up to 50 URLs per payment. | $0.01 |
POST /v1/x402/audit | SEO basics + link/OG health in one call | $0.002 |
POST /v1/x402/map-lite | Site URL list from sitemap/robots + 1-hop crawl (up to 50 URLs) | $0.002 |
POST /v1/x402/video | Scroll-capture a page as MP4/WebM video | $0.005 |
POST /v1/watches | Create a scheduled monitor (free to create, prepay 100-run packs) | $0.10–$1.00/pack |
The same products are buyable with an API key: POST /v1/register
({"address"} → {apiKey}), fund with a plain USDC transfer via
POST /v1/invoice, then send Authorization: Bearer <apiKey> to
POST /v1/extract, POST /v1/audit, POST /v1/map-lite, POST /v1/video,
POST /v1/analyze, or POST /v1/analyze/batch. Every call costs 1 credit,
refunded whenever the call does not return 200; an empty balance answers 402
with a 1-credit top-up invoice. Watches fund the same way:
POST /v1/watches/{id}/topup {"runs": 100} (capture pack 10 credits, extract
pack 100). Full spec: GET /openapi.json (tags: accounts).
| Endpoint | Description |
|---|---|
GET /v1/extract/preview?url=... | Bounded preview: title, headings, links, word count (10 req/min/IP) |
GET /v1/og?url=... | Open Graph link-preview metadata |
POST /v1/watches | Create a scheduled monitor (free; prepay via top-up) |
GET /v1/health | Liveness check |
POST /v1/feedback | Tell webcap something (machine or human): {"message":"…","category?"?:"bug|suggestion|pricing|docs|integration|other","endpoint"?:"…"}. No account, rate-limited 60/hr. Human form: GET /feedback |
webcap ships an MCP server, so any MCP host (Claude Desktop, Cursor, agent frameworks) can call it as a tool. Two ways to wire it: a remote endpoint (no install at all) or the stdio server from a checkout.
The remote endpoint is the cheapest path for an agent — nothing to install, no package registry, no account:
POST /mcp speaks MCP Streamable HTTP (JSON-RPC 2.0 over HTTPS; GET is
deliberately 405 because the server never opens an SSE stream). It holds no
wallet, so it never spends on a caller's behalf: the free tools run directly,
and a paid tool returns the live x402 402 challenge for your own client to
settle. The endpoint is also described in
/.well-known/mcp-tools.json and openapi.json.
It is listed in the official MCP Registry as
io.github.shoutsid-lab/webcap, so a runtime that reads the registry can
discover it without this README:
The stdio server runs locally and can settle paid calls itself. The free tools
need no configuration; set WEBCAP_MCP_WALLET_KEY to a Base-mainnet USDC key to
let the paid tools settle automatically (gasless — the payer signs EIP-3009, the
facilitator pays gas). With no key, paid tools return the x402 402 challenge for
the host to pay. No wallet at all? Set WEBCAP_MCP_API_KEY to an
operator-funded account key instead (POST /v1/register, then fund via
POST /v1/invoice): paid tools bill 1 credit each from that balance. A
configured wallet wins over the key.
From a source checkout — npm ci && npm run build — then point args at
its dist/mcp/stdio.js:
(npm run mcp runs the TypeScript directly, so no build step is needed
there.) The npm release will be @shoutsid/webcap — the unscoped
webcap name belongs to an unrelated package, and it is not published yet —
so until then the remote endpoint above is the install-free option.
Tools, all 18 of them (every one is also in
/.well-known/openai-tools.json and /.well-known/mcp-tools.json):
webcap_preview, webcap_og, webcap_service,
webcap_health, webcap_agent_funnelwebcap_trial_status, webcap_trial_claim_capture,
webcap_trial_claim_extract, webcap_trial_claim_audit,
webcap_trial_claim_map_lite, webcap_trial_claim_analyze,
webcap_quick_thumbnail (no wallet needed)webcap_capture, webcap_extract, webcap_audit, webcap_map_lite,
webcap_video, webcap_analyzeThe trial tools are the point: an agent can claim one real extraction, audit or capture for free before it spends anything.
The live rail is crypto (x402, USDC on Base) — no accounts, no API keys.
Card payments are an operator option, not a hosted feature: until an operator
sets STRIPE_SECRET_KEY, POST /v1/stripe/checkout answers
stripe_not_configured and points at the crypto rail. (The hosted deployment at
https://webcap.shoutsid.fyi is card-less today.)
POST /v1/stripe/checkout with a pack id — Stripe Checkout handles the rest.webcap uses x402 v2 — a gasless, accountless payment protocol built on HTTP 402:
PAYMENT-REQUIRED header carrying a base64 x402 v2 challenge.transferWithAuthorization (from your wallet, to the merchant, for the amount). No ETH needed — the facilitator submits the tx and pays gas.PAYMENT-SIGNATURE header. The facilitator verifies your USDC balance, settles on-chain, and returns the result.No accounts. No API keys. No credits. Just HTTP + your choice of payment.
The packaged MCP server also ships as a GitHub release asset — install it like any npm dependency, without publishing to npm:
For MCP hosts the no-install path stays primary: point them at the remote
endpoint https://webcap.shoutsid.fyi/mcp (streamable HTTP, no package).
The Docker setup includes health checks, resource limits, and persistent data volumes. See docker-compose.yml for details.
All environment variables are documented in .env.example. Key ones:
| Variable | Description | Default |
|---|---|---|
WEBCAP_CHAIN | Network: base, base-sepolia, or local | base-sepolia |
WEBCAP_PUBLIC_BASE_URL | Public URL for artifact links | required |
WEBCAP_X402_PRICE_USDC | Price per screenshot in USDC | 0.001 |
WEBCAP_X402_EXTRACT_PRICE_USDC | Price per extraction in USDC | 0.01 |
X402_FACILITATOR_URL | Payment facilitator endpoint | https://x402.org/facilitator |
Full OpenAPI 3.1 spec: GET /openapi.json
Agent discovery: GET /.well-known/x402, GET /v1/x402/service, GET /llms.txt, GET /skill.md
Both must pass before a change ships. Deliberately no test/file counts here: they
have gone stale twice (a reader caught the second one in issue #1), and a number
nobody regenerates is worse than no number. npm test prints the current totals.
The tests check the code; this checks the claims — it reads README.md,
/skill.md and /llms.txt and verifies every METHOD /path they advertise is
actually served, that every documented price equals the 402 challenge amount, and
that the free trial menu quotes the same prices as the paid routes. It exits
non-zero on any failure, so it can gate a deploy. Issue #1 was filed by an agent
that did this by hand; this is the same check as a command.
MIT — see LICENSE for details.