SingleFax

SingleFax Send a fax from Claude, ChatGPT, Cursor, or any MCP client.

CommunityOnlineNo sign-inGlobalFreeCan modify data

What it can do

  • List Skus: Catalog of SingleFax SKUs with prices. Send a document with create_fax_draft. Get a number with create_inbound_number. Credits with create_checkout. PDF, Word, Excel, PowerPoint, RTF, plain
  • Quote Fax: Retail send quote without charging. Pass to (E.164). Optional pages (default 10) or base64 of the document for a live page count. Optional contentType when MIME is missing.
  • Get Credits: Read prepaid credit balance

What data it sees

Do you need an account

No: the server works without sign-in

SingleFax

Send a fax from Claude, ChatGPT, Cursor, or any MCP client. Upload a PDF, quote pages, pay, and poll delivery status. MCP: https://singlefax.com/mcp (Streamable HTTP + OAuth)
Docs: singlefax.com/agents HIPAA / PHI is not available on MCP. Use the website HIPAA Secure path with an electronic BAA.

Connect

Sign in with OAuth when the client prompts. No API key.

claude mcp add --transport http singlefax https://singlefax.com/mcp

How to connect

How to connect SingleFax to Claude

The server address to paste into Claude settings:

https://singlefax.run.tools

  1. Open Claude (claude.ai or the desktop app).
  2. Go to Settings → Connectors.
  3. Click Add custom connector.
  4. Paste the server address copied below into Remote MCP server URL and click Add.
  5. In a chat, click + → Connectors and switch the new connector on.

Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

Authorization

After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

How to connect SingleFax to ChatGPT

The server address to paste into ChatGPT settings:

https://singlefax.run.tools

  1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
  2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
  3. Open Settings → Connectors and click Create.
  4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
  5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
  6. In a new chat open + → Apps/Connectors and enable the connector.

OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

Authorization

On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

How to connect SingleFax to Cursor

The server address to paste into Cursor settings:

https://singlefax.run.tools

Fastest: click Open in Cursor below and confirm the prompt.

Manually:

  1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
  2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
  3. Save the file. The server appears in the MCP list; authorize it there if asked.

Authorization

If the service needs sign-in, an authorize button appears next to the server in the MCP list.

Server tool list (10)

Raw names from tools/list. Only developers need these.

list_skusCatalog of SingleFax SKUs with prices. Send a document with create_fax_draft. Get a number with create_inbound_number. Credits with create_checkout. PDF, Word, Excel, PowerPoint, RTF, plain text, and images (JPEG, PNG, TIFF, GIF, WebP, BMP, HEIC). Do not convert to PDF first — send the original file. We convert to PDF before sending. HIPAA, EIN, and IRS forms are website-only (URLs included).
quote_faxRetail send quote without charging. Pass to (E.164). Optional pages (default 10) or base64 of the document for a live page count. Optional contentType when MIME is missing.
get_creditsRead prepaid credit balance
get_fax_statusGet fulfillment/payment status for a fax order you own
list_numbersList this account's active inbound fax numbers (E.164, type, expiry). After create_inbound_number checkout completes, call this to read the number.
create_uploadOptional. For files too large for a tool-call. Returns uploadPageUrl (human drop, no login) and uploadUrl (HTTP PUT raw bytes, no Authorization). Pass uploadToken to poll stored, then create_fax_draft.
create_fax_draftSend a fax from this authenticated session. Pass to plus uploadToken from create_upload after the file is stored. base64 only for tiny files (under ~20KB). Optional contentType when sniffing is needed. For larger files: create_upload → user opens uploadPageUrl → create_fax_draft({ to, uploadToken }). Queues on credits or a page pool; otherwise returns checkoutUrl. PDF, Word, Excel, PowerPoint, RTF, plain text, and images (JPEG, PNG, TIFF, GIF, WebP, BMP, HEIC). Do not convert to PDF first — send the original file. We convert to PDF before sending.
create_machine_faxAutonomous MPP path — returns payment_required challenge when unpaid, then charges on retry with payment_authorization
create_inbound_numberReserve a dedicated inbound fax number and return Stripe Checkout. Default sku inbound_30day ($4.99). Also lifetime-basic, lifetime-pro, monthly-basic, annual-basic, monthly-business, annual-business. Optional country US|CA and state. Returns checkoutUrl plus the reserved phoneNumber. After the user pays, call list_numbers. Free 24-hour numbers, vanity digits, HIPAA, EIN, and IRS stay on the website.
create_checkoutStart Stripe Checkout for a catalog SKU. Prefer create_inbound_number for a fax number. sku: credit_pack | inbound_30day | monthly-basic | annual-basic | monthly-business | annual-business | lifetime-basic | lifetime-pro. HIPAA/EIN/IRS are website-only (list_skus). Do not use this to send a document — use create_fax_draft.
SingleFax: connect to Claude, ChatGPT, Cursor · Connectors.fun