https://satohash.io Prove a file existed without revealing it. Bitcoin anchors the fingerprint; OpenTimestamps makes it free and verifiable by anyone, forever. Guides, learn articles, and updates from the Give A Bit family — an open civic tool for truth. en Sat, 29 Aug 2026 22:35:48 GMT https://satohash.io/docs/executive-summary https://satohash.io/docs/executive-summary Why Satohash exists: a free, sovereign, Bitcoin-anchored proof of existence via OpenTimestamps. Hash locally, stamp in minutes, verify forever. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/how-satohash-works https://satohash.io/docs/how-satohash-works Why it is free: a million fingerprints fold into one shared Bitcoin anchor. The plain-English answer plus the full OpenTimestamps technical deep-dive. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-bitcoin-timestamping-vs-notaries https://satohash.io/docs/learn-bitcoin-timestamping-vs-notaries You need to prove that a document existed on a certain date. You have two very different ways to do it: a traditional notary, or Bitcoin timestamping. Here's an honest comparison. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-blockchain-for-archives https://satohash.io/docs/learn-blockchain-for-archives Archives, libraries, governments, and companies all face the same problem: how do you prove a record is authentic and unchanged, decades after it was created? Bitcoin timestamping is quietly becoming Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-eidas-ueta-explained https://satohash.io/docs/learn-eidas-ueta-explained If you've read about digital documents, you've seen these acronyms: eIDAS, UETA, ESIGN. They're the laws that say electronic signatures and electronic records are legally valid. Here's what each one m Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-how-to-prove-a-document-existed https://satohash.io/docs/learn-how-to-prove-a-document-existed Whether it's a contract dispute, a copyright claim, an invention idea, or a receipt, "prove it existed before this date" comes up more often than you'd think. Here's how to do it with Bitcoin. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-how-to-verify-an-ots-proof https://satohash.io/docs/learn-how-to-verify-an-ots-proof You've been handed a .ots file (or you made one). How do you check that it's real? Here's every way, from easiest to most independent. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-ots-vs-docusign https://satohash.io/docs/learn-ots-vs-docusign If you've ever "e-signed" a document with DocuSign, Adobe Sign, or HelloSign, you already trust a company with your document's date record. Here's how Bitcoin timestamping (Satohash + OpenTimestamps) Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-protecting-ai-outputs https://satohash.io/docs/learn-protecting-ai-outputs AI tools (ChatGPT, Claude, Midjourney, DALL-E, Sora…) generate text, images, and video at scale. That raises a real problem: proving when a piece of AI output was created — and proving you didn't edit Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-timestamping-compliance https://satohash.io/docs/learn-timestamping-compliance Compliance teams live in a world of "prove it." Audit trails, retention policies, and evidence of controls are the price of doing business in finance, healthcare, and government. Bitcoin timestamping Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-timestamping-photos-video https://satohash.io/docs/learn-timestamping-photos-video Photos and videos are the easiest things to edit and the hardest to argue about later. A Bitcoin timestamp turns "I think I had this photo then" into "here's the block." Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/learn-what-is-opentimestamps https://satohash.io/docs/learn-what-is-opentimestamps OpenTimestamps (OTS) is a free, open-source protocol that anchors a cryptographic fingerprint of any file into the Bitcoin blockchain. It was created by Peter Todd and has been running since 2016. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/marketing https://satohash.io/docs/marketing Satohash marketing: positioning, the three emotional beats, channels, and assets for a free, honest, Bitcoin-anchored civic tool. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence https://satohash.io/docs/support-and-guidance https://satohash.io/docs/support-and-guidance An honest request to legal, technical, and funding communities: help us harden Satohash, a free, open, Bitcoin-anchored civic tool for truth. Sat, 29 Aug 2026 22:34:10 GMT Satohash — Free Bitcoin Proof of Existence