What is OrangeCheck?

OrangeCheck is a sybil-resistance primitive. A small Bitcoin UTXO, left unspent for time, is the cheapest credible signal of commitment available on the open internet. Every other filter costs trust:

Proof of work costs electricity.
KYC costs dignity and creates a honeypot.
CAPTCHAs cost attention, and break constantly.
Social vouching costs a pre-existing graph.
Bonded sats cost opportunity cost on Bitcoin you already held.

Honest users pay nothing but time. Attackers pay real Bitcoin opportunity cost at scale.

What it proves

A valid OrangeCheck attestation proves three facts cryptographically:

You control a specific Bitcoin address. (BIP-322 signature.)
The address holds N sats right now. (Live chain state via public explorers.)
The bonded UTXO has been unspent for N days. (Confirmation time vs. now.)

And one fact self-assertedly:

The holder claims handles like github:alice or nostr:npub1….

Claims 1–3 are mathematical. Claim 4 is an assertion the signer makes; relying parties verify handle ownership out-of-band (GitHub gist, DNS TXT record, signed Nostr event).

What it is not

Not	Because
Reputation	Reputation implies social judgment. This is a cryptographic stake receipt. Selling it as karma misleads users.
Identity	Address control plus a claimed handle is not proof-of-human.
Custody	Funds never move. The protocol signs a message; it doesn't spend a UTXO.
An account system	No signup, no passwords, no session.
A reputation aggregator	Multi-attestation "unified score" aggregators become walled gardens.
On-chain	Everything is off-chain signed messages. The chain is read, not written.

The one-line pitch per audience

Platforms — drop-in bot filter via GET /api/check?addr=...&min_sats=....
Integrators — npm install @orangecheck/sdk or pip install orangecheck; three functions.
Users — one signature, one shareable URL, no account. Embed the badge anywhere.

Business model

Open-core, always. The protocol and SDK are MIT / CC-BY-4.0 forever. The business lives on hosted convenience and enterprise contracts:

Hosted verifier — free tier for community use; paid tier adds webhooks, SLAs, higher rate limits, custom scoring namespaces, private attestation relays.
Support for @orangecheck/gate — middleware is free; paid integration support for enterprises with on-prem requirements.
Reference infra products — sybil-filtered Nostr relays, airdrop gates — per-distribution fees when we run the infra.

None of these require venture scale to break even. All keep the protocol open.

Why Bitcoin

Bitcoin's opportunity cost of holding is real, measurable, and adversary-agnostic. Ethereum gas is volatile; other-chain reserves aren't credibly neutral. Bitcoin UTXOs give us the cleanest economic signal on the open internet.

Also: the design rule is "if a feature works identically on Ed25519, it doesn't belong here." The Bitcoin economic layer is load-bearing — the whole point.