Get a free key
Proof of existence as an API

Plans & Pricing

Send a hash, get a Polygon-anchored certificate anyone can verify without us. Start free with 100 API proofs a month and pay by volume as your app grows. Every plan makes the same independently verifiable proof.

SHA-256 Fingerprinting Polygon Blockchain Open-source verify-proof Files never stored
Free
Everything you need to build an integration and demo it.
$ 0 / month
  • 100 API proofs a month
  • REST API, webhooks and proof bundles
  • Embeds and public verification pages
  • Web uploads: up to 1,000 a month
Developer
For an app that is live and growing.
$ 19 / month
  • 1,000 API proofs a month
  • Then $0.01 per proof, billed monthly
  • Web uploads: up to 1,000 a month
  • Partner branding on certificates
  • Downloadable certificate packages
  • Email support
Platform
For products that anchor at volume.
$ 79 / month
  • 10,000 API proofs a month
  • Then $0.01 per proof, billed monthly
  • Web uploads: up to 10,000 a month
  • Everything in Developer
  • Your proofs go first in the anchoring queue
  • Team accounts and audit export
  • Support answered within 2 business days
More than 10,000 proofs a month?

Tell us your volume and we will quote a price for it.

Volume pricing Contact us
Included in every plan
Files never stored
SHA-256 fingerprinting
Polygon anchoring
Public verification page, plus an offline check with verify-proof

API allowances reset on the 1st of each month (UTC). On Free, API proofs past 100 are refused until then; on Developer and Platform they continue at $0.01 each. A proof shows that a file existed by a date, not who made it. Certificates are a readable copy. The Polygon transaction and the proof bundle are the record, and anyone can check them without ProofLedger.

Add proof of existence to your app.

Get a free key, send a hash, and give your users a certificate anyone can check without trusting you or us.

Get a free API key Read the API docs

Reference

ProofLedger records a file's SHA-256 hash on the Polygon blockchain and issues a certificate and a proof bundle. The bundle verifies offline with the open-source verify-proof package, so a proof can be checked without contacting ProofLedger. The file itself is never sent. The API needs only its hash, and the file name is optional. The website tool also sends the file's name, size and type, and for photos a few camera details (never location).

A proof shows that a file existed by a date. It does not show who made it or that its contents are true.