Verify a Proof

Hash or upload the content you want to check, then jump straight to its proof details.

Check a Proof

Drop a file here, or click to choose (< 2 GB for browser hashing). Files are never uploaded in Private or Verify mode.

Verification Instructions

How to independently verify proofs without trusting our service

Step 1: Calculate Your File's Hash

Important: For Raw Text

If you have raw text (not a file), first create a .txt file with exactly your text. Make sure to include exactly the same line breaks and spaces as in the original text. Save it, then hash the file using the commands below.

Windows

# Navigate to your file's folder

cd C:\\path\\to\\your\\file

# Calculate SHA-256 hash

certutil -hashfile your-file.txt SHA256

macOS

# Navigate to your file's folder

cd /path/to/your/file

# Calculate SHA-256 hash

sha256 your-file.txt

# Or simply drag the file into terminal:

sha256 [drag file here]

Linux

# Navigate to your file's folder

cd /path/to/your/file

# Calculate SHA-256 hash

sha256sum your-file.txt | awk {'print $1'}

Step 2: Inspect OP_RETURN

After anchoring, you are provided with a Bitcoin transaction ID. Go to mempool.space and paste it in the search box. Then navigate to "Details" and inspect the OP_RETURN value in hex format to confirm it equals your 64-hex hash.

Go to mempool.space:

https://mempool.space

Bitcoin transaction details showing OP_RETURN

Step 3: Verify the Match

Success if:

The OP_RETURN data exactly matches your calculated hash
The transaction has at least 1 confirmation
The transaction timestamp is after you created the proof

Proof TXT Format

Human-readable certificate format for downloaded proofs

Hash (SHA-256): 2ebc80955a1b14c7859738412d4fd1b498b16580fa48bf9cf6bf7d4ca0c5a6c5 Algorithm: SHA-256 (canonicalized NFC+LF+trim) Anchored in Bitcoin: Transaction: 4b8e3a...f02c Block height: 861234 Anchored at: 2025-08-30 14:22 UTC Permanent proof page: https://proofseal.org/proof/2ebc8095... ----- BEGIN CERTIFIED TEXT ----- Hello Bitcoin world. This is my immutable statement. ----- END CERTIFIED TEXT -----

Proof OTS Format

OpenTimestamps standard format for cross-compatible verification

ProofSeal also generates .ots files following the OpenTimestamps standard. This format is widely supported by other timestamping services and Bitcoin verification tools, ensuring your proofs remain verifiable even if ProofSeal is no longer available.

Verification with OpenTimestamps tools:

Name the .ots the same as your original file with .ots extension. document.pdf document.pdf.ots for example.
Use ots verify document.pdf.ots command
Compatible with other OpenTimestamps services
Can be verified independently of ProofSeal