How Fast Sign works
Fast Sign makes a public, verifiable record that a Fast address signed the SHA-256 fingerprint of a file. The file stays in your browser. Fast receives the fingerprint and signed claim, not the file itself.
From a file to a Fast record
- 1
Choose what to sign
Pick a file or paste a 64-character SHA-256 fingerprint. Hashing happens locally.
- 2
Review the exact claim
Choose your relationship to the file and review the fingerprint, signing address, network, and optional public details.
- 3
Approve it in your wallet
Fast App or Fast Wallet Extension signs the unchanged claim with the selected Fast address.
- 4
Settle and verify
Fast settles the claim. Anyone with the file or fingerprint can later check the signing address and on-chain record.
What you can do today
Sign any file or fingerprint
Choose any file and Fast Sign computes its SHA-256 fingerprint in your browser. You can also paste a fingerprint you computed elsewhere, without selecting a file.
Use Fast App or Fast Wallet Extension
Both methods approve the same AAv1 claim format. For each signing ceremony, Fast Sign derives the preview from the exact canonical bytes sent unchanged to the selected wallet.
Say how you relate to the file
Choose authored, co-authored, approved, published, reviewed, witnessed, received, or official release. This is the signer's statement; it is not independent proof of authorship.
Create a signed PDF copy
For supported PDFs, Fast Sign can append a visible signature page and QR code. More people can sign the same original later, without changing the already signed original bytes.
Verify a file or fingerprint
Fast Sign finds recorded settlements, checks their Fast certificates, and compares the fingerprint. A stamped PDF also carries a receipt and a QR link to its verify page, where the settled signatures for that document are shown.
Show useful public context
Where Fast ID resolution is available, Fast Sign can show the address's Fast ID name. A signer can also choose to list signed work on the matching Fast ID public page.
What a Fast Sign result proves
The holder of a Fast address approved a claim containing this fingerprint and chosen relationship, and Fast settled that claim.
The signer's legal identity, authorship, authority to sign for an organization, or whether the result meets a particular legal-signature requirement.
A matching fingerprint means the checked artifact produces the SHA-256 digest committed in the settled claim. For a stamped PDF, Fast Sign verifies the original signed prefix separately from the appended stamp bytes. Whether that evidence is sufficient for a contract, filing, or regulated signature depends on the rules of that use case.
Coming next
These are the next capabilities in the current product and architecture plan.
Historical Fast ID checks
Verification will check whether the signing address was bound to the attached Fast ID when the attestation settled. The result will clearly say verified, pending, invalid, indeterminate, or not applicable.
Stronger settlement discovery
A network backfill and reconciliation tool will recover valid settlements that were not added to the public lookup index by the original browser.
Team and organization workflows
Later versions can add signing requests, multiple signers, organization roles, credentials, and workflow rules on top of the same Fast settlement record.