Document timestamping services compared

Gridcoin Stamp is a free blockchain timestamping service. Your browser hashes the file, the hash goes into a Gridcoin transaction, and the proof is final in a few minutes. You only need to keep the original file. It has run continuously for over five years.

OpenTimestamps is the free choice for Bitcoin anchoring if you can wait a few hours and keep a proof file. OriginStamp suits businesses that want a paid, supported product. FreeTSA is the free choice when a workflow requires the RFC 3161 format. Proof of Existence anchors to Bitcoin for a per-document fee.

Last checked: November 2026.

Side by side

	Gridcoin Stamp	OpenTimestamps	OriginStamp	FreeTSA	Proof of Existence
Price	Free, no account	Free, no account	Commercial, price on request	Free	Paid per document, in bitcoin
Anchored in	Gridcoin blockchain	Bitcoin	Bitcoin and Ethereum	One authority's signing key (RFC 3161)	Bitcoin
Sent to the service	Only the SHA-256 hash	Only the hash	Only the hash	Only the hash	Only the hash
Time until final	Usually a few minutes	A few hours	Up to 24 hours	Instant	After the payment confirms
Keep besides the file	Nothing	The .ots proof file	The certificate or raw proof	The .tsr token and the authority's certificates	Nothing
Check without the service	Any Gridcoin block explorer	A Bitcoin node	Bitcoin or Ethereum explorer and the Merkle path	OpenSSL and the saved certificates	Any Bitcoin block explorer
Developer tools	REST API, GitHub Action, MCP server	CLI and libraries	REST API with key	HTTP with OpenSSL or curl	Small REST API

Gridcoin Stamp vs OpenTimestamps

Where OpenTimestamps is stronger

OpenTimestamps anchors to Bitcoin, the largest proof-of-work chain, and needs no account. Its calendar servers can delay a proof but cannot forge one. It is the strongest choice if Bitcoin's security is the only thing that matters to you.

Where Gridcoin Stamp is stronger

With OpenTimestamps you must keep the .ots file next to the original, and the proof is only complete after Bitcoin confirms it a few hours later. If the .ots file is lost, so is the proof. Gridcoin Stamp confirms in minutes and you keep nothing extra, because the hash itself is enough to find the proof. Every stamp also gets a public proof page and a printable PDF certificate.

Gridcoin Stamp vs OriginStamp

Where OriginStamp is stronger

OriginStamp anchors each batch to both Bitcoin and Ethereum and documents a full manual verification procedure. It is a commercial product aimed at businesses, with support and contracts.

Where Gridcoin Stamp is stronger

OriginStamp anchors once a day, so a proof can take up to 24 hours, and pricing is by quote. Gridcoin Stamp is free and needs no account or API key. A stamp confirms in minutes, and checking it later takes only the original file.

Gridcoin Stamp vs FreeTSA

Where FreeTSA is stronger

FreeTSA is a free RFC 3161 timestamp authority. Responses are instant and the format is understood by PDF signing and code signing tools, which matters when a workflow demands RFC 3161.

Where Gridcoin Stamp is stronger

An RFC 3161 token is only as good as one operator's signing key, and you must keep the token and the authority's certificates. FreeTSA replaced its signing certificate in March 2026, so checking an older token also means keeping the old certificate around. A Gridcoin Stamp sits in a public blockchain that no single party controls, and you keep only the file.

Gridcoin Stamp vs Proof of Existence

Where Proof of Existence is stronger

Proof of Existence was one of the first blockchain notaries. It writes the document hash straight into a Bitcoin transaction, so the proof needs no extra file.

Where Gridcoin Stamp is stronger

Proof of Existence charges a bitcoin fee per document and broadcasts only after that payment confirms. Gridcoin Stamp works the same way on chain, with one hash in one transaction, but you pay nothing and there is no payment to wait for. It also has an API, a GitHub Action and an MCP server.

When to pick something else

Gridcoin is a proof-of-stake chain that has run since 2014, longer than Ethereum, but it is much smaller than Bitcoin. If you want the proof to rest on the largest proof-of-work chain, use OpenTimestamps. If a process or a tool specifically asks for an RFC 3161 token, use a timestamp authority such as FreeTSA. If you need a signed contract and someone to call when things break, a commercial provider fits better.

For everything else (manuscripts, artwork, research data, contracts, software releases) Gridcoin Stamp gives a public, permanent proof in minutes at no cost. Stamp a file, read how to verify a stamp, or automate it with the API, the GitHub Action or the MCP server.

Stamp service wallet balance: 20533.58786991 grc

Address: SHpqN8xEjy2HHTnAGfgJjwFThuqzLbBs6i

Current block height: 4,133,753

Made with ❤ by @gridcat · Part of Gridcoin Club ↗ · ·