Capture the Web as Evidence.
Trustworthy. Irrefutable.

ProofSnap is a Chrome extension that captures web pages as legal evidence with blockchain timestamping, ensuring the authenticity and integrity of digital evidence.

ProofSnap uses OpenTimestamps to anchor a SHA-256 hash of your evidence to the Bitcoin blockchain, creating a cryptographic proof of when the capture was made. This timestamp is independently verifiable and cannot be backdated or tampered with, providing irrefutable proof that your evidence existed at a specific point in time.

ProofSnap offers a 7-day free trial included with all plans. Choose from flexible monthly or annual subscriptions: Essential ($8.99/month or $80/year), Professional ($16.99/month or $160/year), or Enterprise ($24.99/month or $240/year). Annual plans save you 20%.

1. screenshot.png: Image file capturing a visual snapshot of the web page.
2. metadata.json: Contains contextual details about the evidence, such as timestamp, URL, and browser information.
3. manifest.json: Lists all evidence files and their hashes to verify the integrity of the package.
4. manifest.sig: Digital signature for the manifest file, ensuring authenticity and integrity.
5. manifest.json.ots: OpenTimestamps proof file for the manifest.json.
6. publickey.pem: Public key used to verify the digital signature of the manifest.
7. evidence.pdf: PDF document compiling all evidence files for easy sharing and review.
8. domtextcontent.txt: Plain text content extracted from the web page's DOM.
9. page.html: Full HTML content of the captured web page.

To check the integrity of your ZIP archive, upload it to the ProofSnap Trust Verifier and click the Verify manifest button.

1. Unpacking: The ZIP archive is automatically extracted, revealing all included files.
2. Manifest check: The verifier reads manifest.json, which lists each file and its expected SHA-256 hash.
3. Hash validation: For every file, ProofSnap computes its SHA-256 hash and compares it to the value in the manifest.
4. Result display: You’ll see a list of files with their validity status:
   • Valid: The file’s hash matches the manifest.
   • Invalid: The file’s hash does not match, indicating possible tampering or corruption.

Note: ProofSnap uses the SHA-256 hashing algorithm, which ensures strong cryptographic integrity for file verification.

To verify the timestamp of your evidence using OpenTimestamps:

1. Extract the ZIP archive: Unzip your ProofSnap ZIP archive to access its contents.
2. Locate files: Find manifest.json and manifest.json.ots in the extracted folder.
3. Open OpenTimestamps website: Go to https://opentimestamps.org/
4. Upload files: On the website, upload manifest.json.ots as the timestamp proof and manifest.json as the file to verify.
5. Check verification result: The site will show whether the timestamp is valid and anchored on the Bitcoin blockchain.

Note: OpenTimestamps provides cryptographic proof that your evidence existed at a specific time, independently verifiable on the blockchain.

If you have a ZIP archive from ProofSnap and want to confirm its contents haven't been tampered with, follow these steps. ProofSnap uses the SHA-256 hashing algorithm to ensure file integrity.

1. Extract the ZIP archive: Unzip the file to access its contents.
2. Locate the manifest: Find the manifest.json file listing expected SHA-256 hashes for each file.
3. Compute the hash manually:
   • macOS / Linux: Open Terminal and run:
     shasum -a 256 <filename>
   • Windows (PowerShell): Open PowerShell and run:
     Get-FileHash -Path "<filename>" -Algorithm SHA256
4. Compare the result: Match the computed hash with the one listed in the manifest.
   • If they match: The file is valid.
   • If they differ: The file may be corrupted or altered.

ProofSnap generates forensically sound evidence with cryptographic proofs aligned with eIDAS 2 standards for qualified timestamps and digital signatures. Admissibility depends on jurisdiction and specific legal requirements. Consult with legal professionals for specific cases.

Regular screenshots can be challenged in court because they lack proof of when they were taken and whether they've been altered. Courts increasingly require authentication under rules like FRE 901/902 (US) or equivalent rules in other jurisdictions.

ProofSnap addresses these challenges by creating a forensic evidence package that includes: a SHA-256 cryptographic hash proving the content hasn't been modified, a digital signature for authenticity, a blockchain timestamp proving when the capture occurred, and full metadata (URL, browser info, TLS certificate). This makes your screenshot significantly more defensible than a plain image file.

To preserve a web page as court-ready evidence: install the ProofSnap Chrome extension, navigate to the page you need to capture, and click "Capture page snapshot." ProofSnap automatically captures the full-page screenshot, all visible and hidden text, page HTML, metadata, and session data. Everything is bundled into a tamper-evident ZIP archive with cryptographic hashes, a digital signature, and a blockchain timestamp.

This approach is superior to simply saving a PDF or taking a screenshot because it creates a chain of custody with independently verifiable cryptographic proofs. The evidence package can be verified by anyone using the ProofSnap Trust Verifier or by manually checking the SHA-256 hashes and OpenTimestamps blockchain proof.

ProofSnap is optimized for capturing social media and messaging platforms as legal evidence. It supports WhatsApp Web, Messenger, Instagram, Telegram, Discord, Slack, LinkedIn, X (Twitter), Reddit, and Airbnb.

For messaging apps, use the "Full chat capture" option to document an entire conversation history into a single verified file, or use "Capture visible area only" for a specific message or post. ProofSnap captures the content before it can be deleted or edited, and timestamps it on the blockchain so you can prove the messages existed at that point in time.

This is particularly useful for harassment evidence, contract disputes, defamation cases, employment disputes, or any situation where social media content may be deleted.

ProofSnap enables Airbnb hosts to archive all guest communications as legally admissible evidence. Capture messages, reservations, and agreements for disputes, insurance claims, or guest-caused damages.

With regulations like the Digital Services Act (DSA) and updated tax obligations for short-term rental providers, hosts have increasing requirements to maintain records of reservations and communications.

ProofSnap creates a verifiable archive with blockchain timestamp proving communication content at a specific time — ideal for:

• Property condition disputes before/after stays
• Insurance claims and guest-caused damages
• Guest complaints and refund requests
• Documenting contractual terms and agreements

When documenting online harassment, cyberbullying, threats, or defamation, it's critical to preserve the evidence before the perpetrator deletes it. ProofSnap captures the complete web page including the harasser's profile, the offending content, timestamps, and all technical metadata (URL, browser info, session data).

Each capture is protected with a blockchain timestamp and cryptographic hash, creating an evidence package that proves:

• The content existed at a specific date and time
• The evidence has not been altered since capture
• The exact URL and source of the content

This evidence package can be submitted to law enforcement, included in a police report, or presented in court proceedings for cyberbullying, stalking, threats, or defamation cases.

Online content can disappear at any time — posts get deleted, pages get edited, accounts get removed. ProofSnap lets you instantly "freeze" any web page into a tamper-evident evidence package before the content vanishes.

Simply navigate to the page and click capture. ProofSnap saves everything: the full screenshot, the complete HTML source, all visible text content, metadata, and session data. The blockchain timestamp proves exactly when you made the capture, so even if the original content is deleted, you have an independently verifiable record.

This is essential for litigation holds, preserving defamatory content, documenting fraudulent offers, saving terms and conditions before they change, or any situation where you need proof of what a website showed at a specific point in time.

ProofSnap uses three layers of cryptographic protection:

1. SHA-256 Hashing: Every file in the evidence package is hashed. Changing even a single pixel or character produces a completely different hash, making any tampering immediately detectable.
2. Digital Signature: The manifest (listing all files and their hashes) is digitally signed with a private key. The corresponding public key is included for anyone to verify authenticity.
3. Blockchain Timestamp: The manifest hash is anchored to the Bitcoin blockchain via OpenTimestamps, creating an immutable record of when the evidence was captured. This timestamp cannot be forged or backdated.

Together, these mechanisms create a chain of integrity that proves the evidence is authentic, unaltered, and was captured at a specific point in time.