Keymaster is a licensing server you own, for people who sell software. It issues ed25519-signed license keys (KM1.under payloadover .under signatureover ) your apps verify completely offline with just the public key, enforces seat limits with machine fingerprints, delivers builds through signed URLs that expire in 15 minutes, and fires HMAC-signed webhooks on every activation. Keygen.sh starts at $99/mo ($1,188/yr); Gumroad skims 10% + 50¢ off every sale — at $10k/yr in sales that’s over $1,000 a year. Keymaster is $49 once on a $5 VPS, and the signing keypair is yours.

• Ed25519-signed keys, verifiable offline — keypair generated on first boot, owned by you
• Activation API with machine fingerprints, seat limits, and signed receipts for offline runs
• Zero-dependency verification snippets for Node and browsers; key format documented byte-for-byte
• Versioned product releases with artifact uploads behind expiring signed download URLs
• Activation webhooks with HMAC signatures, retries, and a delivery log
• No-login customer portal: paste a key, see seats, download the latest build
• Dark React admin: stats, activation chart, issue/bulk-issue/revoke
• Stripe/Whop key-issuing recipe in the docs

Self-hosted on a $5 VPS for production (Docker included); desktop mode for local key authoring.

What’s included:

• Windows installer download (build via npm run dist)