Docs

Ship mail from your stack.

Production printing and mailing are live. Start in the dashboard, then graduate to API keys and the hosted MCP endpoint. Staging keys (lbl_test_) never purchase postage. People sending one piece can follow the letter guide or the postcard guide.

REST API

OpenAPI 3.1, Bearer lbl_ keys, PDF upload, letters, both postcard types, product quotes, pricing, and address validation.

MCP server

All MCP tools, product artwork specifications, workspace keys, credits, Square checkout and x402 payments.

Developer payments

For integrators: HTTP 402 stablecoin payments (x402) on the API. Workspace customers pay by card.

Fonts

Uploaded PDFs keep embedded fonts. Compose uses Times, Helvetica, and Courier.

Product notes

Create an account, add a from-address, compose a letter, and pay with credits. Top up with a card on Square. Integrators can also use stablecoin payments, documented on the developer payments page. Live health (probed, not a static green light): /status and /status.json.

This production deployment has live printing and mailing. Staging API keys (lbl_test_) never purchase postage — that is a developer sandbox, not a postage-disabled site. Demo environments never submit physical mail. Production quotes may upload artwork for pricing, but only an explicitly confirmed send releases mail. Price checks never release mail.