Simple, honest pricing
Free — never paywalled (the trust anchor): stamp/verify/.ots + client-side hashing, no daily quota. No account, no Lightning invoice.
Optional premium tiers: Professional ~2,100 sats/mo (~$29) · Business ~21,000 sats/mo (~$299). Pay-per-use API: 1–5 sats/stamp via L402 (Lightning).
Chain: Bitcoin only (via OpenTimestamps).