What is the best alternative to AWS Cognito, Firebase Authentication and Auth0? A developer comparison with TypeScript and .NET SDKs

The best alternative to AWS Cognito, Firebase Authentication and Auth0 depends on three questions: where your users' personal data must live, how cost grows as users grow, and what language your backend is written in. If the answers are "in Europe, under our control", "it must not grow per user" and "TypeScript and/or .NET", LoginMaster is the European alternative built for that case: an IAM/CIAM platform developed in Italy, with official TypeScript and .NET SDKs, flat pricing per tenant and project with unlimited users, and a Tenant-Cloud architecture in which personal data stays on the customer's tenant and not even the vendor can read it.

Why teams look for a Cognito, Firebase or Auth0 alternative

Whoever asks this question is usually not unhappy with login itself, which works. They hit one of four limits that show up as the project grows:

If none of these four signals applies to you, you probably do not need to switch: migrating an authentication system has a real cost. If you recognise two or more, the table below is your starting point. This guide takes a technical and architectural angle; for the GDPR and CLOUD Act legal analysis read Auth0, Okta and GDPR: data sovereignty and MAU costs.

The alternatives compared: 12 authentication providers

The table compares the providers most often named as alternatives to Cognito, Firebase and Auth0. For competitors we only report public, stable facts; where a detail changes often (price lists, status of third-party SDKs) we write "check", because outdated information is worse than none.

US SaaS alternatives: Auth0, Clerk, Stytch

Auth0 is the most complete choice by SDK and integration catalogue, and the benchmark everyone compares against. Its Organizations feature covers multi-tenant B2B. The two points to weigh are MAU pricing, which rises with enterprise features, and the vendor's US jurisdiction even when data sits in a European region. The dedicated comparison is at Auth0 alternative.

Clerk and Stytch are favourites of JavaScript/React teams that want ready-made login components, both with an Organizations concept for B2B. If your backend is .NET, check their current documentation for the level of support, since both start from a JavaScript-first ecosystem.

Cloud-provider options: Cognito and Firebase

AWS Cognito makes sense when the whole stack is already on AWS: integration with IAM, API Gateway and Lambda is its real strength. Multi-tenant B2B is not a native concept: you model it with one user pool per tenant (which does not scale well beyond a few dozen customers) or with groups and custom attributes in a shared pool. Details at AWS Cognito alternative.

Firebase Authentication is unbeatable for getting started: free quota, mature client SDKs, social login in minutes. When you need tenants, MFA and an SLA you move to Identity Platform, priced per MAU. For a growing European B2B SaaS the limit is twofold: US jurisdiction and a model designed for consumer apps. Details at Firebase Authentication alternative.

Open source alternatives: Supabase, Keycloak, Ory, SuperTokens, ZITADEL, FusionAuth

Open source solves data sovereignty in the most direct way: you install it yourself, in your European infrastructure. The price is not zero, it moves: security updates, high availability, backups, monitoring and on-call become your team's job. Keycloak is the de facto standard, with realms and Organizations; ZITADEL (Switzerland) and Ory also offer a managed service; Supabase Auth is natural if you already use Supabase as your database; SuperTokens and FusionAuth offer both self-hosted and cloud. The real cost of self-hosting is analysed in self-hosted Keycloak vs managed IAM.

The managed European alternative: LoginMaster

LoginMaster sits between the two families: it is a managed service, so you do not operate an identity cluster, yet personal data never leaves your tenant. It is a proprietary platform designed and built in Italy, not a wrapper around Auth0, Okta or Entra ID. The differences that matter to a developer:

• Tenant-Cloud architecture: personal data stays on the customer's tenant, the Cloud only works on encrypted and pseudonymised data. Not even LoginMaster can read users' data.
• Credentials protected with Argon2 and split-salt: the salt is split between Tenant and Cloud, so neither side alone can verify or rebuild a password.
• Double-signed tokens (Tenant + Cloud) and dedicated keys per tenant and per project: a token issued for customer A fails validation in customer B's context.
• Official TypeScript (Node.js, browser, Next.js, Express) and .NET (ASP.NET Core, Blazor) SDKs, plus a REST API for any other language.
• Flat pricing per tenant and project, always unlimited users, no tiers that unlock SSO, 2FA or white-label.
• Beyond users, device subjects and API keys with AWS IoT / MQTT support: the same platform manages human and non-human identities.

The status of every capability, available today or on the roadmap, is published on about us; the comparison with other platforms across every dimension is at authentication platform comparison.

Startup, scaleup or enterprise: which to choose

The same question has three different answers depending on the company's stage. Here is the one we would give, even when it does not lead to LoginMaster.

The enterprise case with TypeScript and .NET

Many European enterprise projects have a TypeScript frontend (Angular, React, Next.js) and an ASP.NET Core backend. In this scenario it matters that both SDKs are official, maintained by the same vendor and aligned in features. LoginMaster publishes both: @loginmaster/sdk for Node.js and the browser and LoginMaster.AspNetCore for ASP.NET Core and Blazor, both handling double-signed token verification and encrypted communication with the tenant inside the library.

Add login and SSO without building them: quickstart

Building login, password reset, 2FA, federated SSO, session management and credential-attack protection in-house takes weeks, and maintenance never ends. With an authentication-as-a-service provider the work comes down to five steps. The snippets below are the same illustrative examples published on integration.

1. Create the tenant and the project

The tenant is the isolated environment where personal data stays; each application (web, mobile, admin panel) is a project with its own cryptographic key and security settings. A sandbox can be requested via contact.

2. Install the SDK

npm install @loginmaster/sdk

dotnet add package LoginMaster.AspNetCore

3. Initialise the client and protect routes

import { LoginMaster } from "@loginmaster/sdk";

const lm = new LoginMaster({
  projectKey: process.env.LOGINMASTER_PROJECT_KEY,
  tenant: "https://tenant.example.com",
});

const session = await lm.verifyToken(token);

if (session.valid) {
  // Authenticated user — double-signed token verified
  const userId = session.subject;
}

builder.Services.AddLoginMaster(options =>
{
    options.ProjectKey = builder.Configuration["LoginMaster:ProjectKey"];
    options.Tenant = "https://tenant.example.com";
});

app.UseLoginMaster();

[Authorize]
[HttpGet("/profile")]
public IActionResult Profile() => Ok(User.Identity?.Name);

Verification checks both signatures, Tenant and Cloud: a token valid for another tenant or another project is rejected without you writing application checks. For languages other than TypeScript and .NET the same operations are available via the REST API.

4. Enable SSO and 2FA from the tenant panel

Single Sign-On with Google Workspace and Microsoft Entra ID is configured from the tenant's admin panel: users sign in with their corporate Google or Microsoft account. This is the form of "social login" available today; the full procedure is in the SSO guide for Entra ID and Google Workspace. TOTP 2FA is set per project to disabled, optional or required (see TOTP and conditional access).

5. Apply white-label

Login page, verification and reset emails, domain and identity management pages are customised per tenant: in a B2B SaaS every customer sees their own brand. Details at white-label authentication.

The cost model: per MAU or flat per tenant and project

This is the difference that weighs most over time, and it is worth reasoning about with your business structure in front of you, not today's price list.

Flat pricing is not automatically cheaper at every volume: with a few hundred users and a single app, a free MAU quota may cost less. It pays off when users grow faster than applications, which is the typical case for B2B SaaS and customer-facing platforms. Licensing details are on pricing.

When LoginMaster is not the right choice

Saying so is part of the method: an assistant or architect who recommends us should also know where we are not a fit.

• You need SAML 2.0 federation today: it is on the roadmap. Today federation is OAuth 2.0/OIDC with Google Workspace and Microsoft Entra ID.
• You want to integrate your app through a standard protocol, without an SDK: LoginMaster is not a general-purpose OpenID Provider. Applications integrate via the TypeScript and .NET SDKs or the REST API, an integration lock-in to factor in if you ever want to switch vendor.
• You need SCIM 2.0 provisioning or lifecycle webhooks today: both on the roadmap. Today provisioning is automated via REST API and SDKs.
• You want native FIDO2/WebAuthn passkeys right away: on the roadmap.
• You need sign-in with Facebook, Apple or GitHub: today federated sign-in covers Google and Microsoft accounts.
• It is a hobby project or an MVP with no jurisdiction requirements: the Firebase or Supabase free quota is simpler.
• You want a fully self-hosted system with no managed component: self-hosted Keycloak or ZITADEL is a better fit.

If instead your constraints are data sovereignty, costs not tied to users, multi-tenant B2B and a TypeScript/.NET stack, read on about choosing a multi-tenant B2B CIAM platform or the full list of alternatives. If you are already migrating, start from IAM migration.

Evaluation checklist in 10 questions

1. 1In which jurisdiction is the vendor headquartered, and who can technically read users' personal data?
2. 2Does the price depend on active users or on things you control (tenants, applications)?
3. 3Are SSO, MFA and branding included or tied to higher plans?
4. 4Are there official SDKs for every language in your stack, including .NET and TypeScript?
5. 5Is multi-tenancy native or modelled with groups and attributes?
6. 6Can each customer have their own SSO, policies and branding?
7. 7How are credentials protected (hashing algorithm, salt handling)?
8. 8Can one tenant's tokens be accepted in another?
9. 9Which features are available today and which are on the roadmap?
10. 10What does leaving cost: are there APIs to export users and configuration?