Best direct mail API: four options, three with a $0 entry plan, compared by piece price

Best direct mail API: four compared by plan and piece price

For a small team weighing the best direct mail API, three options start at $0 a month: Thanks.io's Pay as you go plan, Lob's Developer plan and PostGrid's Starter plan. Handwrytten, the fourth, lists its Pro plan at $449 a month on Pay Monthly, with API access on every plan, as read on October 24, 2026.

The Thanks.io, Lob and PostGrid prices are 4x6 postcards with postage inside. Handwrytten bills postage on top at the current USPS rate.

Thanks.io API: every plan, test mode and estimates

Thanks.io's pricing page and API answer say the API is on every plan, while one help-center plan table leaves API access and per-recipient AI messaging out of the Free column, so confirm API access for your plan when you sign up. One POST request sends one piece to one recipient, and the API has no batch minimum.

Every send endpoint has a matching estimate endpoint, which prices an order with nothing charged. A postage_class field picks first_class or standard on a send or estimate request, and Standard Mail is a paid-plan class. API testing mode submits orders without generating real mail or charges.

API usage bills against your account balance, and with auto-recharge off, a send is blocked if it would take the balance below $0. Previews from the API carry a DRAFT watermark on Pay as you go and Business.

Lob and PostGrid: print-and-mail APIs for developers

Lob sizes plans by yearly mailings and users. Developer is $0 a month for up to 6,000 mailings and 1 user. Startup is from $260 a month for up to 75,000 mailings and 3 users, and Growth is from $550 a month for up to 150,000 and 5 users.

Lob bills its print and postage rate beside the plan fee, with 4x6 postcards at First Class from $0.905, $0.645 and $0.615 across the three plans, per Lob's help center. Thanks.io vs Lob sets it against Thanks.io.

PostGrid's Starter is $0 a month for up to 500 mailings a month, 1 user and 10 templates, with a test account and API docs. Thanks.io vs PostGrid and PostGrid alternatives cover the rest.

Handwrytten API: pen-written cards by code

Handwrytten says custom handwriting robots hold real pens. Its pricing page says all plans include API access, QR code tracking and multistep campaigns. Pro is $449 a month on Pay Monthly or $374 a month on Pay Annually, plus $1.99 a card. Monthly plans are billed every 4 weeks.

Webhooks, test modes and overage limits

Thanks.io's webhooks need Business at $49 a month or Professional at $199 a month, and fire on order status, delivery and QR scan events. The Zapier, Make and Integrately connectors also need a paid plan, so a Pay as you go account calls the API from code. PostGrid offers a test account and Thanks.io an API testing mode.

On overage, PostGrid says a fee applies above 500 mailings a month and prints no amount, and Lob's pricing page states no overage price.

Pick Thanks.io for an API that sends handwriting-style pieces on a plan with no monthly fee, with Business adding webhooks. Pick Lob for plans sized by yearly mailings, PostGrid for letters, postcards and checks under 500 mailings a month, and Handwrytten for pen-written cards. The Thanks.io API runs on Pay as you go at $0 a month, so a developer can wire it up before any plan fee.