OB3 Proof

Prove your document existed.
Timestamp it on blockchain forever.

Any file. Any document. Any creative work. Upload it, get a SHA-256 hash, and anchor that hash permanently on the Polygon blockchain. Undeniable proof of existence at a specific date and time.

Create a Proof -- from $4.95Verify a Proof
$4.95
Starting price
Per document
SHA-256
Hash algorithm
Industry standard
Forever
Proof lasts
On Polygon blockchain
Free
To verify
Anyone, anytime
Who Uses OB3 Proof

Proof of existence for anything that matters

Musicians and Songwriters
Timestamp your original recordings and compositions before releasing or pitching them. Prove you wrote it first if your work is ever stolen or plagiarized.
Photographers and Artists
Anchor your original photos and artwork with a permanent timestamp. Prove authorship in DMCA disputes and licensing negotiations.
Writers and Authors
Timestamp manuscripts, screenplays, articles, and books before submission. Prove your work predates any similar published work.
Software Developers
Anchor your source code, algorithms, and technical inventions. Establish prior art before filing patents or open sourcing your work.
Businesses and Contractors
Timestamp contracts, proposals, invoices, and agreements. Prove what was agreed to and when, before any dispute arises.
Researchers and Academics
Anchor research findings, data sets, and reports before publication. Establish the timeline of your discoveries.
How It Works

Your file stays private. The proof is public.

01
Upload Your File
Select any file up to 50MB. Your file is hashed in your browser -- it never leaves your device on the Basic plan.
02
SHA-256 Hash
A unique cryptographic fingerprint is computed. If even one character in your file changes, the hash changes completely.
03
Blockchain Anchor
The hash -- not your file -- is anchored on Polygon mainnet with a permanent timestamp. Immutable. Forever.
04
OB3-PRF Code
You receive a proof code. Anyone can verify your document has not changed by re-hashing and comparing to the blockchain record.

Your File Stays Private

On the Basic plan, your file is hashed entirely in your browser using the Web Crypto API. The hash is what goes to our server and onto the blockchain -- not the file itself. On Content and Legal plans, you can optionally store an encrypted copy with us so you can prove the original file later if needed.

Pricing

Simple one-time pricing

Basic Proof
$4.95
Contracts, evidence, business documents
+SHA-256 file hash
+Polygon blockchain anchor
+Permanent timestamp
+OB3-PRF code
+Public verify page
+File hashed in browser
Most Popular
Content Proof
$9.95
Musicians, photographers, writers, artists
+Everything in Basic
+Encrypted file storage
+Author attribution
+Download original anytime
+DMCA support letter
+Certificate PDF
Legal Proof
$19.95
Legal evidence, IP disputes, declarations
+Everything in Content
+Notary-style declaration
+IP timestamp certificate
+Priority review
+Court-ready documentation
+Attorney letter template
Video

Watch how it works

See how easy it is to get started in minutes.

3
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Prove it existed. Protect what you created.

Starting at $4.95. One-time payment. Permanent blockchain proof. Verification is always free for anyone, forever.

Create My First Proof

OB3 Proof · Onboard3 · A BlockUserve Company