FaxOnline

npx add-mcp 'https://faxonline.app/mcp/fax'

FaxOnline / Agent connections

Let your agent prepare the fax.

Connect over MCP to prepare a PDF fax to a US number, review the checkout link, and track delivery. You authorize the send.

Copy a prompt Connect your agent Read the agent skill

$7.00 per fax · No subscription · No account

Transmission sequence

1. 01

   Agent prepares

   PDF + recipient → price and checkout link

2. 02

   You authorize

   Review the number and complete Stripe checkout

3. 03

   FaxOnline transmits

   Agent checks status; payment captured on delivery

Hand this to your agent

Replace the number and email below, copy the prompt into your agent, and attach your PDF there. Copying this prompt does not upload a document or send a fax.

Your fax prompt Use FaxOnline to prepare the PDF I attach as a fax. Recipient US fax number: [FAX NUMBER] Delivery notification email: [EMAIL ADDRESS] Read the workflow at https://faxonline.app/.well-known/agent-skills/send-fax-online.md and connect to https://faxonline.app/mcp/fax over Streamable HTTP, or use FaxOnline's WebMCP tools in a compatible browser. If you cannot connect, help me set up the connection instead of claiming the fax was prepared. Ask me for any missing document or recipient details. Use prepare_fax, then show me the destination, filename, price, and checkout link. Wait for me to complete checkout to authorize sending; do not complete payment for me. Keep the draft token private and reuse it with identical inputs for retries. After checkout, use get_fax_status no more than once every 15 seconds. Report the actual status; processing is not delivered. Do not create another fax if transmission is uncertain.

Copy prompt

Your agent needs remote MCP or browser WebMCP support. You can also select and copy the prompt manually.

Connect over MCP

Choose a remote MCP server in your client and use this endpoint with Streamable HTTP. No API key is required. Keep each fax’s private draft token secret.

https://faxonline.app/mcp/fax

For clients that accept an mcpServers configuration with a remote URL:

{
    "mcpServers": {
        "faxonline": {
            "url": "https://faxonline.app/mcp/fax"
        }
    }
}

Some clients use a settings screen instead of JSON. Select Streamable HTTP and paste the same endpoint. This service does not provide a local stdio command.

Two tools, one fax

Tool	What it does
prepare_fax	Stores your PDF and returns the price and Stripe checkout link. Requires draft_token, fax_number, email, filename, and document_base64. Preparation does not transmit the fax.
get_fax_status	Returns payment and delivery status for the private draft_token. Poll no more than once every 15 seconds. Processing does not mean delivered.

Generate the token from 32 cryptographically random bytes, encoded as 64 lowercase hexadecimal characters. Reuse the same token and identical inputs for preparation retries. PDF limit: 10 MiB. Destinations: US fax numbers.

Completing checkout authorizes transmission. We capture payment after the provider reports success. Never automatically create another fax after an uncertain transmission; the provider may have accepted the original.

Try discovery without sending a fax

Run these commands to initialize a connection and read the tool schemas. They do not upload a document, create checkout, or send a fax.

curl 'https://faxonline.app/mcp/fax' \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  --data '{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-06-18","capabilities":{},"clientInfo":{"name":"faxonline-example","version":"1.0.0"}}}'

curl 'https://faxonline.app/mcp/fax' \
  -H 'Content-Type: application/json' \
  -H 'Accept: application/json, text/event-stream' \
  --data '{"jsonrpc":"2.0","id":2,"method":"tools/list"}'

Once connected, ask your agent: “Prepare this PDF as a fax to my recipient’s US fax number. Use my notification email and show me the price and checkout link before sending.” Supply the actual document, number, and email privately.

Browser agents and WebMCP

FaxOnline registers tools with compatible browser agents visiting the site. The PDF preparation and status tools use the same backend as remote MCP. Browser tools also expose pricing and a handoff to the send form. Availability depends on your browser and agent’s WebMCP support.

Server manifest Agent overview Current pricing

Agent fax FAQ

What does an agent need to connect?

A client that supports remote MCP over Streamable HTTP. Connect to https://faxonline.app/mcp/fax. No API key or FaxOnline account is required.

Can the agent send a fax without my approval?

Preparing a fax stores the PDF and returns a Stripe checkout link. You review the destination and authorize payment in checkout before transmission is queued.

How much does an agent fax cost?

One outgoing US fax costs $7.00. There is no subscription. Payment is authorized at checkout and captured after the provider reports successful delivery.

Which documents and destinations are supported?

The MCP tools accept PDF documents up to 10 MiB and US fax numbers. Encode the PDF bytes as standard base64, without a data URL prefix.

How does WebMCP discovery work?

A compatible browser agent can discover tools registered by the FaxOnline page it is visiting. Remote MCP clients connect directly to the endpoint. Client support varies.

{"@context":"https://schema.org","@type":"FAQPage","mainEntity":[{"@type":"Question","name":"What does an agent need to connect?","acceptedAnswer":{"@type":"Answer","text":"A client that supports remote MCP over Streamable HTTP. Connect to https://faxonline.app/mcp/fax. No API key or FaxOnline account is required."}},{"@type":"Question","name":"Can the agent send a fax without my approval?","acceptedAnswer":{"@type":"Answer","text":"Preparing a fax stores the PDF and returns a Stripe checkout link. You review the destination and authorize payment in checkout before transmission is queued."}},{"@type":"Question","name":"How much does an agent fax cost?","acceptedAnswer":{"@type":"Answer","text":"One outgoing US fax costs $7.00. There is no subscription. Payment is authorized at checkout and captured after the provider reports successful delivery."}},{"@type":"Question","name":"Which documents and destinations are supported?","acceptedAnswer":{"@type":"Answer","text":"The MCP tools accept PDF documents up to 10 MiB and US fax numbers. Encode the PDF bytes as standard base64, without a data URL prefix."}},{"@type":"Question","name":"How does WebMCP discovery work?","acceptedAnswer":{"@type":"Answer","text":"A compatible browser agent can discover tools registered by the FaxOnline page it is visiting. Remote MCP clients connect directly to the endpoint. Client support varies."}}]}