Fax MCP: The PayPerFax Model Context Protocol Server

A fax MCP server for the chat app you already use. Your assistant prepares the fax from inside the chat. You open the link, see the preview with the price, and pay in the browser. No account, no key, no subscription. Nothing is sent and nothing is charged before you pay.

The fax MCP server from PayPerFax turns a chat app into a way to send one fax, without leaving the chat window. It is the same pay-per-fax service that lives at payperfax.com, opened up through the Model Context Protocol so that Claude – and other chat apps as they ship native MCP connector support – can prepare the fax for you.

The server

https://fax.payperfax.com/mcp

Remote, Streamable HTTP, no authentication. You add it once in your chat app’s connector settings. There is no password, no API key, and nothing to sign up for.

Nothing is sent and nothing is charged before you pay. The MCP server does not pay. A person pays through the link, in the browser. A fax that fails to transmit is not charged.

Add the fax MCP server to your chat app

The exact path depends on the app. In most chat apps that support MCP today, the three steps are the same.

Open the connectors or integrations settings. Look for a section named “Connectors”, “Integrations”, “MCP servers” or “Tools”. Native MCP connector support arrived in Claude first; other chat apps are catching up.
Add a custom MCP server. Pick “Add a custom MCP server” (the wording varies). Give it a name – “PayPerFax” is fine – and the URL https://fax.payperfax.com/mcp. The transport is Streamable HTTP, with no authentication.
Turn the connector on in your chat. Open the chat where you want to send the fax and enable the connector. The three PayPerFax tools are now available to the assistant.

Tell your assistant which country you are in, so the price shows in your currency and the dates read in your format. You can also tell it which language you want for the preview, the payment page and the emails: English, Spanish, German, French, Japanese or Korean.

The three tools, in plain language

Tool	What it does
`create_fax`	Prepares a fax and returns a link for you. The assistant gives the destination number, your email address, and either a letter it wrote or a notice that a file is still needed.
`get_fax_status`	Reads the status of a fax that was already prepared. The values are the same as the tracking page: queued, sending, delivered or failed.
`list_supported_formats`	Lists the input types, the size limits and the languages. The assistant can read this if it needs to check what is possible before it prepares the fax.

The assistant never pays and never sends on your behalf. The link, the preview and the payment are yours.

The preview link is good for four hours. The pre-filled form link, used when a file is still needed, is good for twenty-four hours.

MCP prepares the fax. The browser carries the file.

MCP does not transfer files from a chat app to the server. The assistant cannot hand bytes to PayPerFax through this door. The service is built around that limit, with two ways to work with it.

If the assistant writes the document. A letter the assistant drafts from your notes travels along as text. It is sent in the markdown field of the call, becomes the first page of the fax, and renders as a plain black-on-white document. Headings, lists, tables and code are kept.
If you have the file. A signed form, a scan or a PDF you were sent stays on your device. The assistant prepares the fax with a notice that a file is expected. The link in the answer opens the pre-filled web form, with a short line that reads “Your AI assistant prepared this fax”. You add the file in the browser and continue from there.

The split is the point. The chat app does the writing, the picking of a number and the filling of fields. The browser does the file and the payment. Together they send one fax.

If your assistant runs in a shell (Claude Code, Codex, Cursor), it can also skip MCP and send the file over HTTP directly. The MCP server and the HTTP service are the same thing. See the PayPerFax API for the HTTP path.

What this is not

The fax MCP server is for one person sending one fax from a chat app. It is not an MCP service to embed faxing into a product.

There are no accounts and no API keys. There is nothing to sign up for.
There are no webhooks, no callbacks, no fax list, no inbound fax. The assistant reads the status from the tracking page the same way you would.
The assistant does not pay. A person pays, in the browser, every time.
There is no sending without a payment step. “Pay per fax” is literal: one fax, one payment.
It is not an email-to-fax subscription product.

If you are building a system that embeds faxing (a healthcare platform sending thousands of referral faxes a day, a loan servicer with its own fax workflow, an EHR), you need a different kind of service. We are not it.

If your chat app has no MCP connector yet

Native MCP connector support is still rolling out across chat apps. A chat app without it is not left out. Two short paths cover almost everyone.

A coding agent with a shell. Claude Code, Codex and Cursor can call the PayPerFax API over HTTP, with the same shape of request and the same preview link back. The pay-per-fax API page has the detail: the PayPerFax API.
A chat app with no shell and no connector. Plain ChatGPT, Gemini, and Claude without the connector set up still help in the plainest way: the assistant writes the letter and hands you a PDF, a DOCX or a Markdown file. You upload it on the form at fax.payperfax.com. If the assistant can read web pages, it can also read the status back from the tracking page after you pay.

For a plain-language breakdown of what each chat app can do today, see can ChatGPT or Claude send a fax for me?.

Price

The fax MCP server uses the same pay-per-fax pricing as the website. There is no MCP tier.

$2 covers the first three pages (one optional cover page plus two document pages).
$0.75 covers each page after that.
A fax that fails to transmit is not charged.

The preview link shows the final guaranteed price before you pay. Billing is in your local currency where supported: USD, EUR, GBP, JPY or KRW. The full destination list and the per-country rates are on the pricing page.

Documentation

The setup page for the fax MCP server lives on the PayPerFax documentation site, with the field shapes, the rate rules and a short note on the country field.

MCP server reference: the server URL, the three tools, the two call shapes of create_fax, the country and language fields, and the rate rules.
Guide for AI assistants: the plain-language page for an assistant that is about to prepare a fax.
Send a fax (HTTP): the fields of the create call, with examples. The MCP tool create_fax is the same call.
Check the status: the status values and the polling rules.

The documentation is in English only. The link pages that you and the fax recipient see (preview, filled form, tracking) are in six languages: English, Spanish, German, Japanese, Korean and French.

Short FAQ

Which chat apps can use the fax MCP server today?

Any chat app with native MCP connector support. Claude was the first and the setup is one short step in Connectors. Other chat apps are catching up as they ship the same kind of support. If your chat app does not have it yet, the API fallback path still works: a coding agent with a shell can call the HTTP service directly, and a chat app with no shell can draft the letter for you to upload on the form.

Does my assistant pay for the fax?

No. The assistant prepares the fax and hands you a link. You open the link, see the preview with the price, and pay in the browser. Payment is always a person at a browser, every time.

Do I need an account to use this?

No. There is no sign-up on the website for a single fax, and nothing for your assistant to register either. The fax MCP server has no API key and no password. If a service ever requires an account to send one fax, it is not this one.

Can my assistant send a file through MCP?

Not through MCP itself. MCP does not transfer files from the client to the server. A letter the assistant writes travels along as text in the markdown field. A file you already have (a signed form, a scan, a PDF) is added by you in the browser after the assistant prepares the fax. A coding agent with a shell can also send the file over the HTTP service directly.

Is it safe to let an assistant start a fax for me?

The assistant only prepares the fax. It cannot pay. It cannot send without you. Every fax has a preview link that only you open, and the preview shows the exact document and the exact fax number before you pay. The connection to PayPerFax uses TLS, and documents are deleted after 30 days. The full policy is on the security page.

Fax MCP: Prepare a Fax from Your Chat App