Proof Holdings vs Firebase Auth
Firebase Authentication is Google's user login and directory — free to start, superb mobile SDKs, wired into Google Cloud. Proof Holdings is a verification layer that returns a portable proof token, with no user store and no cloud lock-in. Different jobs.
Keep Firebase for free basic login on Google Cloud. Add Proof for what it can't give you: domain verification, human approvals over messaging, and a portable signed proof of every check — priced per proof, not per MAU.
One API · One key
One key does what a stack of vendors does
Every platform on this page wants to run your user directory. Proof is a single API you call from your own stack — the same reverse-OTP flow issues a signed, offline-verifiable ES256 token for each of these:
Flat price · Any asset
One flat price for every asset — phone, email, and domain today, with wallet and social coming soon. No per-seat, no per-MAU, no per-verification tiers — the meter that makes every rival's bill jump.
- Free every month
- 300 proofs
- Pay as you go
- €0.03 / proof
- At volume
- €0.0079 / proof
Feature Comparison
Swipe to compare →
| Feature | Proof Holdings | Firebase Auth |
|---|---|---|
| Core job | Verify asset control → portable proof token | Authenticate users → session + user record |
| Requires a user store | No | Yes |
| Phone / email verification | Reverse OTP (Telegram, WhatsApp, SMS), magic link | Email link + phone SMS OTP |
| Domain verification | DNS TXT, HTTP, admin email, auto-verify | No |
| Wallet / social | Coming soon | Social login (live) |
| MFA | Reverse-OTP flow doubles as 2FA | Identity Platform upgrade only (not classic free) |
| SSO / SAML / OIDC | No | Identity Platform only ($0.015/MAU) |
| Output | ES256 proof token — portable, offline-verifiable | Firebase ID token (JWT), Google-issued |
| HITL approvals for AI agents | Telegram/WhatsApp with signed tokens | No |
| Mobile SDKs | REST + MCP (176 tools) | Best-in-class (iOS, Android, Flutter, Unity) |
| Pricing model | Per-proof (any asset type) | Free classic tier; per-MAU on Identity Platform |
| Cloud lock-in | None — portable tokens | Google Cloud (tokens, Admin SDK, functions) |
Pricing
Pricing model
Proof Holdings
Per-proof: €0.0079 (Business), any asset type.
Firebase Auth
Classic Firebase Auth: free (no MFA/SAML). Identity Platform: 50k MAU free, then $0.0055/MAU (Tier 1); SAML/OIDC $0.015/MAU.
Cheapest at small scale
Proof Holdings
300 proofs/month free
Firebase Auth
Free — classic Firebase Auth has no MAU ceiling for basic email/social/phone
MFA & SSO
Proof Holdings
2FA is built into the same reverse-OTP flow, no upgrade
Firebase Auth
Require the paid Identity Platform upgrade (not in classic free)
Portability
Proof Holdings
ES256 token verifiable by anyone, offline, no lock-in
Firebase Auth
Google-issued ID tokens; identities are coupled to Google Cloud
A verification layer, not a user store
Firebase Authentication logs users into your app and keeps a record of them. Its mobile SDKs and drop-in UI are the best in the market, and basic email/social/phone auth is effectively free at any scale — as long as you live inside Google Cloud.
Proof Holdings doesn't store users or run a cloud. A person proves control of an asset — phone, email, domain (wallet and social coming soon) — and you get a portable token that verifies offline anywhere. You can build passwordless, account-less login on it (Proof authenticates its own users this way); it just isn't a hosted user store like Firebase.
Free — until you need MFA or SSO
Classic Firebase Auth is actually free with no MAU cap for basic sign-in. The catch teams hit: MFA, SAML/OIDC SSO, and multi-tenancy aren't in the free tier — they require the paid Identity Platform upgrade (50,000 MAU free on Tier 1, then $0.0055/MAU; SAML/OIDC at $0.015/MAU). And phone sign-in bills per SMS on top.
Proof Holdings prices one way: €0.0079 per proof on Business, 300 free per month, and its Reverse-OTP flow doubles as passwordless 2FA with no separate tier. Firebase wins on free basic auth for a Google-Cloud app; Proof wins when you want portable proofs, domain verification, or 2FA without an upgrade path — and no cloud lock-in.
When to use Firebase Auth
- You're building a mobile or web app already on Firebase / Google Cloud
- You want the best mobile SDKs and drop-in auth UI in the market
- Basic email/social/phone login, free with no MAU ceiling, is enough
- You want auth wired directly into Firestore, Cloud Functions, and GCP
- You're fine with identities coupled to Google Cloud
When to use Proof Holdings
- You need to verify asset control without storing users
- You need domain verification (DNS/HTTP/admin-email), which Firebase doesn't do
- You want a portable, offline-verifiable proof token with no cloud lock-in
- You want passwordless 2FA without paying for the Identity Platform upgrade
- You want human-in-the-loop approvals over Telegram/WhatsApp with signed tokens
- You'd rather pay per verification than per monthly active user
Frequently Asked Questions
Ready to try Proof Holdings?
300 free proofs per month. No credit card required.
Building with an AI agent? The 176-tool MCP server and test mode let an agent run a real verification right now — machine quickstart in llms-full.txt.