Testimonials your visitors can verify.
Tamper-evident, timestamped proof for the testimonials you already have, anchored on the Bitcoin blockchain so anyone can check them for themselves.
An installable skill for Claude Code and Cursor. CAPTNS verifies the testimonials you have, it does not collect them. Runs offline.
SHA-256 recomputed · verified in your browser
Anyone can paste a five-star quote. Nobody can check it.
Testimonials are the most persuasive thing on your page and the least accountable. CAPTNS makes each one independently checkable, so trust does not depend on taking your word for it, or ours.
Capture, anchor, embed.
The whole capture-and-verify path runs offline. Anchoring on-chain is an opt-in step you take with your own wallet.
Capture and hash
Record a testimonial with its author, source and consent. CAPTNS canonicalises it and takes a SHA-256 fingerprint of the exact text.
offlineAnchor on Bitcoin
Optionally write that fingerprint to the Bitcoin blockchain with your own wallet, batching many at once. This timestamps the text and proves it has not changed since.
opt-in · your walletEmbed a verifiable badge
Drop the testimonial into your page with a Verified badge. A visitor can recompute the hash and check the chain record themselves.
any frameworkCAPTNS hashes any file or testimonial offline and anchors on Bitcoin (BSV) only when you choose. Works inside Claude Code, Cursor and VS Code.
This is the whole trust primitive.
Below is a real testimonial and its published fingerprint. Press Verify and your browser recomputes the SHA-256 and compares. Change one character and it stops matching. Nothing is sent to us.
fa50c28484ef58591f7b1a4fd87ddfaaec9d06326098c2b2c04631e22fcebf12
press Verify
txid a1f4…9c2b · open in a Bitcoin explorer
A proof record, not a claim.
Each entry names the item, its SHA-256 fingerprint, when it was recorded and whether it is anchored on-chain. Recompute and verify runs offline and is free. Anchoring on Bitcoin (BSV) is the opt-in step you take with your own wallet.
Proof record - 3 items, all verified offline · 1 anchored on-chain · northwind-coffee (sample)
| Item | SHA-256 | Recorded | Anchor | Verified |
|---|---|---|---|---|
| testimonialDana Reyes - "Best flat white beans I've bought online. Reorder is one tap and delivery is always on time." | fa50c284…2fcebf12 | 2026-07-07 | anchored · BSVtxid a1f4…9c2b | |
| fileconsent/dana-reyes.consent.txt - captured consent for the testimonial above. | e516ceda…77d0cb00 | 2026-07-07 | not anchoredready-to-broadcast payload | |
| filetestimonials/northwind-coffee.export.json - the canonical testimonial library. | 44dd49ff…2031d931 | 2026-07-08 | not anchoredready-to-broadcast payload |
Part of the upskill suite.
CAPTNS ships as the review and notary skills in the installed upskill suite. They fingerprint, verify and anchor the testimonials you already have, and call uxplate to style them and Theme Tanker to colour them.
Works with Claude Code and Cursor · offline core · early access.
Free to capture and verify. Pay to anchor at scale.
Capturing, hashing, embedding and verifying is free and runs offline, forever. Anchoring proofs on-chain at scale is the paid step, and it comes included with upskill Pro: one subscription unlocks the Pro tier of every skill in the suite.
Capture, hash, embed and verify. Emit a ready-to-broadcast payload you anchor yourself. Offline, forever.
Start freeManaged, Merkle-batched anchoring at scale, hosted verify badges and private testimonial libraries. One upskill Pro subscription covers this skill and every other in the suite.
Get Pro, US$149/yr Pay 2 BSV/yr2 BSV/yr is ~US$50, our Bitcoin community rate.
upskill Pro is one subscription across the whole suite: colour, design, growth & proof. Buy Pro, unlock everywhere. See the suite →
One proof method, from a quote to a whole brand.
CAPTNS is the proof method for saving captions and attestations to chain: free to capture and verify, paid to anchor at scale. Testimonials are where it starts. These are directions we are building toward, not features you can use today.
Short "captn" quotes and memes
Fingerprint a caption, a one-liner or a meme the same way as a testimonial, so a short quote can be traced back to who said it and when.
Provable, attestable testimonials
Pair captured consent with an on-chain fingerprint so a testimonial is both provably unchanged and attestably sourced.
Brand attestation
Extend the same proof to brand statements and claims, so a brand can stand behind what it publishes with a check anyone can run.
Trust primitives
Capture, hash, verify and anchor as reusable primitives that other skills in the upskill suite can build on.
Delivered as the review and notary skills in the upskill suite. /up:review hash and /up:review verify are free;
/up:review anchor is the paid, on-chain step.
Frequently Asked Questions
What does anchoring actually prove?
That the exact testimonial text existed at a point in time and has not been changed since. It does not, by itself, prove a real customer said it. Proof comes from the captured consent and the source link stored with each testimonial, not from the chain.
Does it phone home?
CAPTNS itself makes zero network calls when capturing, hashing, embedding and verifying. Anchoring is the only networked action, it is opt-in, and it uses your own wallet or node. Two honest caveats: the coding agent you run it inside, such as Claude Code or Cursor, may send data back to its own provider, which is outside our control; and what you anchor is a fingerprint (a SHA-256 hash, never the testimonial text itself), written to a public blockchain permanently and immutable by design, so it can never be edited or removed. The free tier stops one step short of broadcast and hands you a ready-to-send payload.
Do I need cryptocurrency to use it?
Not for the free, offline tier. You only need a funded wallet if you choose to anchor fingerprints on-chain, where you pay the network transaction fee to post them. We use the BSV blockchain because it is built for this: its Teranode software is designed to handle over a million transactions a second with fast settlement and ultra-low fees, so posting a fingerprint to chain typically costs less than a cent, and batching drops it further.
Can a visitor really verify without trusting CAPTNS?
Yes. Verifying is a SHA-256 recompute plus a lookup of the fingerprint on any public Bitcoin explorer or their own node, run in their browser. A CAPTNS-hosted checker is a convenience, never the only path.
What about consent and privacy?
Every proof record stores who gave the testimonial and that they consented. Anchoring a fingerprint is not a substitute for consent or for the testimonial-disclosure rules in your market, and CAPTNS never claims it is.