See how Proof compares.

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.

Vonage Verify earns its place — Silent Network Authentication confirms a number at the carrier level with zero taps, elegant where coverage reaches. What's left in your hands afterward is the question: a platform fee, per-country SMS charges, and a status flag that evaporates. Same job with Proof; you keep the proof.

Sinch's flash call is real engineering — a missed call instead of an SMS, cheaper at scale where Android and carrier support line up. The catch hides in 'where it lines up': Android-only, pricing that shifts by country, and a pass/fail you can't take with you.

Telesign is hard to beat on two things: phone intelligence — PhoneID's risk scoring is strong — and negotiated US SMS rates that are tough to undercut for domestic, high-volume traffic. But Telesign publishes no price, and most users aren't domestic: international SMS runs $0.05–0.50+ a message.

Bird is a capable omnichannel engagement platform — SMS, WhatsApp, email, RCS, Instagram in one place — and if that's what you're buying, verification rides along. Bought as verification alone, it's a marketing suite with layered fees and a pass/fail at the end.

Plivo's $0 verification fee is a real edge for US-only, high-volume SMS — and its AI Fraud Shield blocks the SMS-pumping attacks that plague OTP. The fine print: '$0' still means full per-country SMS costs, and you're left holding a status flag.

Infobip is enterprise CPaaS done properly — omnichannel 2FA with automatic SMS→WhatsApp→RCS→Voice failover and global carrier reach. But failover is a fix for a problem Reverse OTP doesn't have — and every fallback attempt bills again, on top of a monthly base and per-country rates.

Auth0 verifies identity — who someone is. Proof Holdings verifies control — what someone controls. Prove a user owns a phone, an email, or a domain without collecting identity documents or building a user database.

Stytch is a full customer-auth platform — logins, sessions, and a user store you run. Proof Holdings verifies control of an asset and hands back a portable, signed proof token. Both are passwordless; only one issues an attestation you can give to a third party.

Descope builds customer auth with a no-code, drag-and-drop flow editor — logins, sessions, and multi-tenant user management. Proof Holdings verifies control of an asset and returns a portable, signed proof token. Same passwordless moment; a different job around it.

Okta is the enterprise identity backbone — workforce SSO, governance, and a full user directory. Proof Holdings is a verification layer: prove control of an asset, get a portable proof token, no directory required. Different jobs — here's exactly where the line falls.

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.

AWS Cognito is Amazon's user directory and federation, tightly wired into IAM. Proof Holdings is a verification layer that returns a portable proof token, with no directory and no AWS lock-in. Two different jobs — and Cognito's free tier is smaller than most people think.

Cisco Duo is the workforce MFA standard — it protects employee logins to corporate apps with push, WebAuthn, and device trust. Proof Holdings is a customer-facing passwordless verification layer: prove control of an asset, get a portable proof token, no app to install. Workforce versus customer — here's exactly where the line falls.

Twilio Verify is the OTP-delivery anchor for a second factor — the widest set of 2FA channels behind one API. But it returns a pass/fail; Proof returns a signed, offline-verifiable proof of the second factor itself.

Auth0's adaptive MFA is strong if you already run auth there — just budget for it, since MFA sits on the paid tiers. Proof is the passwordless second factor as a standalone primitive: no user directory, a portable proof token.

Cognito gives AWS stacks free TOTP MFA wired into IAM. Proof is a passwordless, account-less second factor that hands back a portable proof — no directory, no AWS lock-in.

A Slack Block Kit approve/deny bot is quick to prototype and free on Slack's platform. But you build and maintain the endpoint, the signature verification, and the storage — and you never get a portable proof of the decision that a third party can verify. Proof Holdings is that approval flow as a turnkey API with a signed token.

Retool is where teams build internal tools and workflows, and it can gate them with human approval steps. Proof Holdings is a purpose-built approval API that returns a portable proof token. Different scope — a platform you build on versus a primitive you call.

n8n is a source-available, self-hostable automation platform with a genuine human-approval step. Proof Holdings is a managed approval API that returns a portable proof token. The real split isn't 'no account' — n8n delivers over Telegram too — it's turnkey plus signed proof versus build-and-host-it-yourself.

Zapier now has a native approval step, so this isn't 'Zapier can't do approvals.' It's that a Zap logs the decision in your account while Proof Holdings hands you a portable, signed proof — and Zapier's reviewers need a Zapier account, while Proof's approvers need nothing but Telegram or WhatsApp.

Windmill is a fast open-source workflow engine with a genuine suspend-until-approved step. Proof Holdings is a managed approval API that returns a portable proof token. A self-hostable OSS platform versus a turnkey primitive — and a secret approval link versus a signature.

Inngest is a superb durable-execution platform — its waitForEvent primitive can pause an AI agent for a human, but you build the notification, the UI, and the record yourself. Proof Holdings is the packaged approval: request, human decision over Telegram/WhatsApp, portable proof token back.

HumanLayer pioneered human-in-the-loop approvals for AI agents — then pivoted, in late 2025, to an AI coding IDE. Its founder now calls the original approval SDK "pretty much all deprecated." If you came looking for HumanLayer's approval API, here's what happened and the purpose-built alternative.

SIWE (ERC-4361) is the open standard for proving control of a wallet a user already owns — the verify-don't-provision idea, done right and free. Proof Holdings productizes that same idea across assets with a portable proof token and a managed API. Wallet verification is coming soon; the model is live today for phone, email, and domain.

Privy (now part of Stripe) is best-in-class at creating embedded wallets from an email or social login — it runs the key infrastructure. Proof Holdings never touches a key: it verifies control of a wallet the user already owns (coming soon), the way it verifies phones, emails, and domains today.

Dynamic (now part of Fireblocks) provisions embedded wallets and connects external ones, and its RS256 token is offline-verifiable, just like Proof's. The real split is the job: Dynamic's headline is creating and operating wallets; Proof verifies control of one you already own, with no key infrastructure. Proof's wallet verification is coming soon.

Web3Auth — now MetaMask Embedded Wallets — derives non-custodial key shares from a social login (MPC): wallet creation as a service. Proof Holdings is the opposite motion — verify what already exists, hold no key material at all — for wallets (coming soon) as for phones, emails, and domains today.

thirdweb is an all-in-one web3 developer platform — wallets, contracts, and SIWE-based auth. Its Auth is aligned with the verify-don't-provision idea, but it issues a first-party token for its own stack; Proof Holdings issues a neutral proof anyone can check. Proof's wallet verification is coming soon.

Magic — once famous for the magic link, now embedded-wallet infrastructure — provisions non-custodial wallets and runs the key infrastructure at scale. Proof Holdings runs no keys: it proves control of assets a user already holds — wallets included, coming soon.

Veriff publishes its prices — rare in KYC — and does regulatory identity properly: government ID plus biometric selfie, AML screening included. Proof Holdings answers a lighter question first: is there a real, reachable person behind this account? No documents, no identity data, a fraction of the cost.

Onfido — now Entrust Identity Verification — brings 2,500+ document types and Atlas AI to regulatory KYC. When the law requires that, use it. Proof Holdings covers the moments before and beside it: prove control of a phone, email, or domain with no ID, no identity data, and no sales call.

Sumsub sells full-cycle KYC/AML/KYB — and its own pricing splits 'non-regulated' from 'regulated' tiers, conceding that plenty of verification isn't compliance work. That non-regulated slice is exactly where Proof Holdings lives: asset control with no identity data, before or instead of a Sumsub check.

Jumio is the enterprise KYX incumbent — deep document-and-biometric identity for regulated onboarding at scale, priced by sales conversation. Proof Holdings is the self-serve layer underneath: filter bots and throwaways from €0.0079 a check before a Jumio verification ever runs.

Persona turns identity checks into configurable "building blocks" — OpenAI, Reddit, and Roblox run KYC and age assurance on it. Proof Holdings is the block that comes before any of that: a no-identity-data control check that filters fraud before you pay for a document flow.

Ondato is EU-native KYC with rare price transparency — from €0.50 per verification, AMLD/GDPR/eIDAS-aligned, out of Lithuania. Proof Holdings (also EU-built) handles the step before compliance: prove asset control from €0.0079, and collect nothing a regulator would ever ask you to protect.

DocuSign is the document e-signature leader — the default for signing a contract today, with the audit trail to match. Proof Holdings signs a different thing: control of an asset, minted as an ES256 token that is itself an electronic signature on the eIDAS ladder. Documents are Proof's roadmap; authorization is its present.

Dropbox Sign (formerly HelloSign) is the developer's way to embed document signing — clean API, lower price point. Proof Holdings is API-first about a different signature: proof that a person controls an asset, as an eIDAS-recognized electronic signature you can verify offline.

Adobe Acrobat Sign is document e-signature inside Acrobat, with the strongest QES path via the Adobe Approved Trust List. Proof Holdings sits at the other end of the eIDAS question: its everyday proof tokens are signatures carrying the technical hallmarks of AES — no PDF involved.