How do I install Postbag?

Copy the stdio config for Cursor, Claude Desktop, Claude Code, or VS Code on this page. It uses the publisher's install, not a PlugMCP proxy.

Does Postbag need an API key?

The publisher lists these environment variables: POSTBAG_API_KEY, POSTBAG_API_URL.

What transport does Postbag use?

Postbag runs locally over stdio.

Postbag

Q: When was Postbag last checked?

Last checked 2026-10-16. Form backend that routes: one tool per Postbag API operation, plus quickstart and explain.

by dev.postbag

Form backend that routes: one tool per Postbag API operation, plus quickstart and explain.

Power your agent

Add this server

The publisher's own command. Not a PlugMCP endpoint.

Local command

npx -y @postbag/[email protected]

Credentials from the publisher

POSTBAG_API_KEY — A Postbag API key (pb_live_… or pb_test_…). Mint one at https://postbag.dev/app or with `postbag login`.
POSTBAG_API_URL — Base URL of the Postbag API. Defaults to https://postbag.dev — set this only for a self-hosted instance.

Provider

Add in Claude

Claude Code

POSTBAG_API_KEY=<secret> POSTBAG_API_URL=<value> claude mcp add dev.postbag-mcp -- npx -y @postbag/[email protected]

Run in a terminal.

Claude Desktop

{
  "mcpServers": {
    "dev.postbag-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@postbag/[email protected]"
      ],
      "env": {
        "POSTBAG_API_KEY": "<secret>",
        "POSTBAG_API_URL": "<value>"
      }
    }
  }
}

claude_desktop_config.json

Step-by-step: add this in Claude

Remote URL or a command on your machine? How the two installs differ

Run on PlugMCP

Host a copy with our keys and logs.

A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.

Launch

Related MCP

Related skills

View all

Postbag

A form backend that routes. Point any HTML form at a Postbag endpoint and it lands in your inbox — then goes wherever it should: email, Telegram, a webhook, a partner, your CRM. Built for people who run many sites, and for the AI agents that build them.

<form action="https://api.postbag.dev/s/fm_8f3kq2" method="POST">
  <input name="email" type="email" required>
  <textarea name="message"></textarea>
  <button>Send</button>
</form>

That's the whole integration for one form. Everything else — grouping forty forms into one stream, mapping their different fields onto one shape, sending that shape to a partner between two dates, a daily digest, never losing a submission — is there when you need it and invisible when you don't.

New here (human or AI agent)? Read CLAUDE.md first.

Why it exists

Every website has forms. Every form needs somewhere to go. Formspree and friends solve "somewhere" for one site; they fall over when you have fifteen sites feeding one partner with fifteen slightly different forms. Postbag is the source of truth for what each form collects, what each downstream system receives, and the versioned contract between them.

The one idea

The database makes it correct; events make it fast.

A submission is accepted the instant it is a row. Delivery is a durable outbox that a worker drains with retries. Realtime nudges are an accelerator, never a transport. If every event stream in the system died, every submission would still arrive — late, never lost. (Inherited from the lead pipeline this generalises; see docs/ARCHITECTURE.md.)

Status

Phase 1 — MVP live at postbag.dev (site, docs, dashboard at /app, API at /v1). See PROGRESS.md for the live blueprint and docs/ROADMAP.md for phases.

Documentation

Start at docs/README.md.

License

The server, dashboard, site and domain packages (apps/*, packages/core, packages/db, packages/auth) are licensed under AGPL-3.0. The client packages that run inside your own code — @postbag/sdk, the postbag CLI and @postbag/mcp — are MIT. Rationale in ADR-006.

Postbag

by dev.postbag

Form backend that routes: one tool per Postbag API operation, plus quickstart and explain.

Power your agent

Add this server

The publisher's own command. Not a PlugMCP endpoint.

Local command

npx -y @postbag/[email protected]

Credentials from the publisher

POSTBAG_API_KEY — A Postbag API key (pb_live_… or pb_test_…). Mint one at https://postbag.dev/app or with `postbag login`.
POSTBAG_API_URL — Base URL of the Postbag API. Defaults to https://postbag.dev — set this only for a self-hosted instance.

Provider

Add in Claude

Claude Code

POSTBAG_API_KEY=<secret> POSTBAG_API_URL=<value> claude mcp add dev.postbag-mcp -- npx -y @postbag/[email protected]

Run in a terminal.

Claude Desktop

{
  "mcpServers": {
    "dev.postbag-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "@postbag/[email protected]"
      ],
      "env": {
        "POSTBAG_API_KEY": "<secret>",
        "POSTBAG_API_URL": "<value>"
      }
    }
  }
}

claude_desktop_config.json

Step-by-step: add this in Claude

Remote URL or a command on your machine? How the two installs differ

Run on PlugMCP

Host a copy with our keys and logs.

A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.

Launch

Related MCP

Related skills

View all

Postbag

<form action="https://api.postbag.dev/s/fm_8f3kq2" method="POST">
  <input name="email" type="email" required>
  <textarea name="message"></textarea>
  <button>Send</button>
</form>

New here (human or AI agent)? Read CLAUDE.md first.

Why it exists

The one idea

The database makes it correct; events make it fast.

Status

Phase 1 — MVP live at postbag.dev (site, docs, dashboard at /app, API at /v1). See PROGRESS.md for the live blueprint and docs/ROADMAP.md for phases.

Documentation

Start at docs/README.md.