# SendFax.sh

> Send real faxes over HTTP. One API call, paid per page with x402 or MPP (USDC) -- no account, no API key. Humans can send via Stripe Checkout.

SendFax.sh is a single-purpose service: send a fax. Agents call a paid HTTP API and settle per request in USDC over x402 or MPP; there are no accounts and no API keys, because the payment itself is the credential. Humans use a drag-and-drop page and pay with Stripe (Link, card, or crypto). Faxes are delivered via Telnyx Programmable Fax and are real-time: the PDF is streamed to the carrier and deleted after sending -- we never store your document. The carrier is HIPAA-compliant (real-time T.38, nothing stored on either end) and SOC 2 Type II, ISO 27001, PCI DSS and GDPR certified. There is no per-transaction minimum and no credit top-up: a one-page fax costs one page.

Pricing is $0.05 per page. On the agent rails (x402/MPP) there is no minimum; the human Stripe flow floors at Stripe's $0.50 minimum charge.

Destinations: SendFax currently delivers to the US, Canada, Mexico, and St. Pierre & Miquelon; a number outside those countries returns HTTP 422.

Support: support@sendfax.sh

## Docs

- [Quickstart](https://sendfax.sh/quickstart.md): send a fax in four steps, with the 402 payment handshake shown end to end.
- [Integration guides](https://sendfax.sh/guides/index.md): index of the platform guides -- every page has a markdown twin at /guides/{slug}.md.
- [HTTP wire format](https://sendfax.sh/guides/http.md): the language-agnostic protocol reference -- every request and response, the multipart shape, both 402 dialects verbatim, idempotent retry semantics, the status lifecycle, and the problem+json error table.
- [Paying with USDC](https://sendfax.sh/guides/usdc.md): the protocol-level guide -- full 402 anatomy, the exact-amount rule, Base + the USDC contract, direct-transfer settlement, refunds, end-to-end curl.
- [Paying with MPP](https://sendfax.sh/guides/mpp.md): the MPP dialect -- the WWW-Authenticate: Payment challenge decoded field by field, its relationship to x402, and what settles today.
- [Sending via curl](https://sendfax.sh/guides/curl.md): the no-dependency reference implementation -- 20 lines of bash for the wallet path, plus the Stripe Checkout path.
- [Sending with TypeScript](https://sendfax.sh/guides/typescript.md): the `sendfax` npm SDK end to end on Node 18+/Bun/Deno, a PaymentHandler wired to a local key with viem, and the plain-fetch version.
- [OpenAPI spec](https://sendfax.sh/openapi.json): OpenAPI 3.1 description of every endpoint, the 402 payment responses, and the schemas.
- [Authentication](https://sendfax.sh/auth.md): there is no auth -- payment is the credential (x402/MPP per request); humans use Stripe Checkout.
- [Agent skill](https://sendfax.sh/SKILL.md): a portable, paste-ready skill describing how to send a fax. Installable into any agent with `npx skills add DanielSinclair/sendfax.sh --skill sendfax -g`.
- [MCP server](https://mcp.sendfax.sh/mcp): remote, authless MCP endpoint (Streamable HTTP; SSE fallback at /sse) exposing send_fax, get_fax_status, and get_payment_instructions. Connect: claude mcp add --transport http sendfax https://mcp.sendfax.sh/mcp

## Optional

- [API page](https://sendfax.sh/docs): the human-readable API page -- curl 402 handshake, pricing, and the machine-readable discovery links.
- [Agent setup guides](https://sendfax.sh/guides): connect an assistant -- Claude (claude mcp add / skill / connector), ChatGPT (developer-mode MCP server), Codex (codex mcp add --url), Hermes Agent, and OpenClaw, each with the exact install command.
- [Platform guides](https://sendfax.sh/guides): working code for Next.js/React, Cloudflare Workers, native macOS and iOS (Swift), React Native, TypeScript (Node/Bun/Deno), and curl.
- [TypeScript SDK skill](https://github.com/DanielSinclair/sendfax): the `sendfax` npm SDK usage skill for agents writing TS/JS -- `npx skills add DanielSinclair/sendfax --skill sendfax-sdk -g`.
- [llms-full.txt](https://sendfax.sh/llms-full.txt): every doc inlined into one file (full API reference, pricing, privacy).
- [About & colophon](https://sendfax.sh/index.md): the markdown twin of the homepage, with the pricing table and font attribution.