Best Alternatives to Auth0 for Cost-Conscious Startups

The Growth Penalty Problem

Auth0's per-MAU pricing model creates what startups increasingly call a "growth penalty" — the more users you acquire, the more you pay, and the costs scale aggressively. Auth0's Essentials plan starts at $150/month for just 500 MAU included, with the Professional tier at $800/month and Enterprise at custom pricing.2 Enterprise SSO connections add $1,100/year per connection, and machine-to-machine tokens cost $35/month per 1,000.2 Even multi-environment setups (dev/staging/prod) require separate tenants, effectively tripling your cost.2

The numbers get stark at scale. At 50,000 MAU, Auth0's B2C Essentials plan runs roughly $1,750/month — while Supabase or Firebase would cost you $0.1 At 100,000 MAU, Auth0 climbs to around $5,250/month.1 Auth0's paid plans have seen substantial price increases, including a 300% per-MAU hike for the Essentials tier.7

The free tier doesn't offer much relief either. Auth0's free tier covers up to 7,500 MAUs (later expanded to 25K),7 but SSO and MFA are gated behind paid plans, and Auth0 tends to push customers toward the Enterprise plan quickly.4

The Alternative Landscape

The good news: a wave of open-source and generously-free-tier alternatives has matured to the point where they cover the vast majority of what startups actually need — OIDC, SAML, MFA, social login — without the per-MAU billing trap.

Supabase Auth offers 50,000 MAU on its free tier and includes 100,000 MAU in its $25/month Pro plan, with overage at just $0.00325/MAU — the lowest per-user rate among managed providers.1

Clerk provides the best developer experience for Next.js and React teams, with a free tier up to 10K MAU (50K on annual billing) and a Pro plan at $20–25/month.1

SuperTokens is fully open-source: self-host for free, or use the managed service starting at $25/month, with no vendor lock-in.3

Logto is built on OAuth 2.1, OIDC, and SAML, with an open-source core that's self-hostable and no per-user pricing lock-in.4

Keycloak offers the maximum control option — fully open-source, $0 license, deep customization, and no vendor lock-in (you pay only in operational overhead).3

The Self-Hosted Identity Stack

Here's where the strategy gets interesting for cost-conscious teams. The most aggressive cost play isn't just swapping one managed auth provider for another — it's pairing an open-source auth layer (Keycloak, SuperTokens, or Logto) with a self-hosted identity and secrets backbone. This eliminates per-MAU billing entirely while centralizing machine identity and secrets management.

That's the thesis behind our picks below. None of these are drop-in Auth0 replacements on their own — but together with an open-source auth layer, they form the infrastructure anchor for teams who want to keep identity costs predictable and near-zero as they scale. The things actually worth buying aren't always the most expensive; sometimes they're the ones you run yourself.

Our Picks

1. HashiCorp Vault — The Self-Hosted Identity Backbone

Vault is the infrastructure anchor for the "avoid per-user pricing" thesis. It's not a drop-in Auth0 replacement — you'll pair it with an open-source auth layer like Keycloak or SuperTokens — but as a centralized secrets and machine-identity store, it eliminates the per-MAU billing that makes Auth0 expensive at scale. Open-source under the MPL, free to self-host, and battle-tested at enterprise scale. The trade-off is operational complexity: you're running your own infrastructure, and that means someone on your team owns uptime.

2. Infisical — Open-Source Secrets Without the Ops Burden

If Vault feels like too much operational overhead, Infisical is the lighter-weight alternative. It's open-source with a generous free tier, self-hostable, and designed to be approachable for startup teams. Pair it with a self-hosted auth layer and your identity-and-secrets spend stays near zero. The managed cloud option exists for teams that want to offload operations without jumping to enterprise pricing.

3. Doppler — Managed Secrets for Teams That Don't Want to Self-Host

Not every startup wants to run its own secrets infrastructure. Doppler offers a managed secrets manager with a free tier and affordable paid plans — simpler than Vault, no servers to maintain. It complements a cheap or free auth provider (Supabase, Clerk, or a self-hosted Keycloak) to keep overall identity spend low without the operational burden of full self-hosting.

4. AWS Secrets Manager — For Teams Already in the AWS Ecosystem

If your stack runs on AWS, pairing Cognito (AWS's native, inexpensive auth) with AWS Secrets Manager gives you a coherent identity-and-secrets story without leaving the ecosystem. The pay-per-secret model ($0.40/secret/month plus API call charges) can still beat Auth0's MAU billing at scale, especially for teams with many users but relatively few secrets to manage.

5. Azure Key Vault — For Teams in the Azure Ecosystem

The Azure counterpart for startups using Entra ID (formerly Azure AD) as an Auth0 alternative. Key Vault provides centralized secrets management with per-operation pricing that keeps costs predictable and non-MAU-based. If your infrastructure is already Azure-native, this is the natural pairing — Entra ID handles authentication, Key Vault handles secrets, and neither charges you per monthly active user.

Disclosure: We may earn a commission from links on this page. That doesn't influence our editorial assessments — we recommend tools based on how well they solve the problem, not on payout.

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