Proof Holdings vs Twilio Verify
Twilio Verify is the default SMS OTP for a reason — battle-tested, and in the US it just works. You're probably thinking 'another OTP vendor.' The difference is what you're holding afterward: Twilio's pass/fail disappears; Proof's Reverse OTP has the user send the code — nothing to intercept — and leaves you a signed token you can verify offline.
If a code that arrives is all you need, Twilio is enough. Teams pick Proof to keep the proof — a signed ES256 token per verification you can show an auditor, a partner, or an agent — from €0.0079 a proof, a fraction of Twilio's $0.05 plus SMS fees.
One API · One key
One key does what a stack of vendors does
Every provider on this page delivers codes to phones. Proof is a single API — the same reverse-OTP flow also covers email and domains, and every verification mints a signed, offline-verifiable ES256 token for each of these:
Same price · Any asset
The same price for every asset — phone, email, and domain today, with wallet and social coming soon. No per-seat or per-MAU fees — the meters that make rivals' bills jump.
- Free every month
- 300 proofs
- Pay as you go
- €0.03 / proof
- At volume
- €0.0079 / proof on the €79 plan
Feature Comparison
Swipe to compare →
| Feature | Proof Holdings | Twilio Verify |
|---|---|---|
| Phone verification | Telegram, WhatsApp, SMS | SMS, Voice, Push, SNA |
| Email verification | Magic Link, OTP | OTP |
| Domain verification | DNS TXT, HTTP, Admin Email, Auto-Verify | No |
| Wallet verification | Coming soon (8 chains planned) | No |
| Social verification | Coming soon (12+ platforms planned) | No |
| Reverse OTP | Yes | No |
| Cryptographic proof tokens | ES256 JWT, offline-verifiable | No |
| Human-in-the-loop approvals | Telegram/WhatsApp with proof tokens | Push (requires your mobile app) |
| MCP server for AI agents | 167 tools | Alpha (limited) |
| Code delivery | No code to deliver (user sends it) | Codes can fail to arrive (Microsoft has reported SMS delivery as low as 50% in some regions) |
| No code in transit to intercept or phish | Yes | No |
| Free tier | 300 proofs/month | No |
| Identity documents required | No | No |
Pricing
Cost per verification
Proof Holdings
From €0.0079/proof (any asset type)
Twilio Verify
$0.05/verification + SMS fees
Free tier
Proof Holdings
300 proofs/month (Pay as you go)
Twilio Verify
No free tier
Multi-asset cost
Proof Holdings
Same price for phone, email, domain (wallet & social soon)
Twilio Verify
Phone + email only. Domain/wallet require separate services
Monthly plans
Proof Holdings
Pay as you go (€0.03), then €9/mo (1K), €29/mo (3K), €79/mo (10K)
Twilio Verify
Usage-based only, no volume discounts below enterprise
Reliability
Twilio Verify sends an SMS or voice call TO the user. Some codes never arrive, lost to carrier filtering, number portability and country-specific rules: Microsoft has reported SMS delivery as low as 50% in some regions. Failed delivery = failed verification = lost user.
Proof Holdings uses Reverse OTP: the user sends a message TO the service via Telegram, WhatsApp, or SMS. Since the user initiates the message, no code has to reach the user. If the user can open Telegram and type a code, verification succeeds.
0
Codes sent to the user (Proof)
50%
Lowest SMS delivery rate Microsoft reported for some regions
10
Live verification channels (Proof)
Security
SIM-swap attacks are the biggest vulnerability of SMS OTP. An attacker convinces a carrier to transfer the victim's number to a new SIM, then receives all SMS codes. Twilio Verify is vulnerable to this attack vector.
Reverse OTP sends no code, so there is nothing to intercept in the network, read off the phone or phish on a fake page. On Telegram and WhatsApp the proof comes from the messaging account, not just the number: a SIM swap alone is not enough — the attacker must also take over the account, which two-step verification blocks when the user has turned it on. On plain SMS, whoever holds the SIM can still send the message.
Every Proof Holdings verification produces an ES256-signed JWT proof token that can be verified offline using our published public key. No API call needed. Twilio returns a status flag (verified/unverified) with no cryptographic attestation.
Proof Tokens
When verification completes on Proof Holdings, you receive an ES256-signed JWT token. This token proves:
- Which asset was verified (a phone, email, or domain today; wallet & social coming soon)
- When the verification happened
- That the proof hasn't been tampered with
The token can be verified offline using the public key. Share it with partners, store it for compliance, or validate it in automated pipelines without contacting the Proof API.
Twilio Verify returns a verification status. There is no portable proof that verification occurred.
AI Agent Integration
Proof Holdings has a dedicated MCP server with 167 tools covering verification, human approvals, asset management, proof validation, billing, and more. Works with Claude, LangChain, CrewAI, OpenAI Agents SDK, and any MCP-compatible framework.
Human-in-the-loop approvals let AI agents request human permission before irreversible actions. The human receives the request via Telegram or WhatsApp, taps Approve or Deny, and the decision is returned as a signed proof token.
Twilio released an alpha MCP server in March 2025 with limited capabilities. Twilio Push can send approve/deny notifications but requires your own mobile app with their SDK, and doesn't produce cryptographic proof of the decision.
When to use Twilio Verify
- You only need phone or email OTP and are targeting US/Canada where SMS delivery is reliable
- You already use the Twilio ecosystem (Programmable SMS, Voice, etc.) and want unified billing
- You need Silent Network Authentication (carrier-level zero-interaction verification)
- Your users won't use Telegram, WhatsApp, or even reply to an SMS — and you'd rather push codes to them
When to use Proof Holdings
- You need verification AND authentication for phone, email, or domain (wallet & social coming soon)
- You want cryptographic proof of every verification, shareable and offline-verifiable
- You operate internationally where SMS delivery is unreliable
- You need human-in-the-loop approvals for AI agents or automation
- You want to prove asset control without collecting identity documents
- You need a combination of verified assets (phone + email + domain) as an alternative to KYC
Frequently Asked Questions
Ready to try Proof Holdings?
300 free proofs per month. No credit card required.
Building with an AI agent? The 167-tool MCP server and test mode let an agent run a real verification right now — machine quickstart in llms-full.txt.
Sources for the SMS delivery figures: Microsoft, “It's Time to Hang Up on Phone Transports for Authentication” (2020-11-10).