Features
Everything required to put paper in the mail — and to let software do it for you.
For people
Upload PDF or compose
Drop a finished document or write a letter in a focused editor.
Address book
Save senders and recipients. Reuse them in the send wizard.
Save from send
One click on the send screen stores sender or recipient in the address book.
Tracking
Job statuses from queued through mailed, with USPS tracking when LetterStream returns it.
For mail classes
First-Class
#10 letters. $1.49 for page 1, then $0.25 per extra page.
Certified Mail
$12.99 base certified piece (first page included), plus $0.25 per extra page.
Electronic Return Receipt
Optional $2.40 ERR add-on on Certified pieces.
Postcards
4×6 color pieces at a flat $1.99.
For software
REST API
Create letters, list jobs, validate addresses, quote prices.
API keys
lbl_live_ and lbl_test_ keys, hashed storage, revoke anytime. CSV lists via the API.
MCP
send_letter and companions for Claude Desktop, Cursor, and other MCP clients.
Cards + USDC
Square for credit cards. HTTP-native x402 payments on Base and Solana.