Auth0 or Build Your Own Login?
Building your own login means taking responsibility for passwords and security yourself – a risk few should take. Auth0 and similar services solve that but get expensive at large user bases. Middle paths like self-hosted Keycloak and cloud providers' built-in identity services often strike the best balance between security, cost, and control.
Almost every digital product needs a login, and the question comes up early: should we build it ourselves or buy a ready-made service like Auth0? It sounds like a technical detail, but at its core it’s a risk question. Handling users’ passwords is one of the most sensitive responsibilities a product can take on, and most should think carefully before taking it. Here’s the trade-off, with security at the center.
Why building your own login is riskier than it looks
Building a login form is easy. Building secure password handling behind it isn’t. That’s where the trap lies.
When you handle passwords yourself, you take on storing them encrypted the right way, protecting them against repeated guessing attempts, handling resets securely, and keeping pace with security practices that keep evolving. Every part has pitfalls, and a single mistake can lead to your users’ passwords leaking. Since many people reuse passwords, a leak on your end becomes a problem far beyond your own service.
This is an area where specialized vendors invest heavy resources and have teams that work on nothing else. Competing with that on your own, as a side task in product development, is rarely wise. The basic rule becomes: don’t build password security yourself unless you have very good reasons.
What a bought service solves – and costs
Auth0 and similar identity services exist precisely to remove that risk. They handle the passwords, the login flows, resets, and protection against attacks, and you get a ready-made, proven login system to plug in. You avoid owning the most sensitive part and can spend your time on your own product.
The price comes in two forms. One is lock-in: you place a central function with an external vendor. The other, more tangible one, is the cost at scale. The pricing model is often based on the number of active users, which makes the service cheap or free at the start but increasingly heavy as the user base grows into the tens of thousands. Certain features also sit behind pricier tiers.
That makes a bought service an excellent choice early on and for many products, but something to calculate carefully if you expect a large user base. The cost at your future scale matters more than the price at launch.
The middle paths
Fortunately, the choice isn’t only between building everything yourself and buying an expensive service. Two middle paths solve password security without leaving you without control or with an unexpected bill.
Open-source Keycloak. Keycloak is an open identity solution you host yourself. It provides the same core functions as a bought service – login, user management, single sign-on – without a per-user license cost. In return, you’re responsible for operations, updates, and keeping it secure. That requires expertise, but you keep full control and avoid a cost that runs away with your user count.
Cloud providers’ built-in identity services. If you’re already running in a cloud, the platform likely has its own service for login and user management. It carries password security for you and integrates smoothly with everything else you already have there. The cost is often lower than a standalone service, and you get a well-maintained solution as part of the deal. The price is that you become more locked into that particular platform.
A concrete scenario
Say you’re building a service you believe could reach a hundred thousand users over time. Building your own password handling would mean taking on a risk you don’t need. Choosing Auth0 right away solves security elegantly, but at a hundred thousand active users, the user-based pricing model can become a substantial ongoing cost.
A common way to think about it: start with what gets you going fastest without sacrificing security, but make the choice with scale in mind. If you’re already running in a cloud, its built-in identity service can offer both safety and reasonable cost from the start. If you expect a very large base and have the operational expertise, self-hosted Keycloak can pay off over time. The point is to choose deliberately based on where you’re headed – not to get stuck in the false choice between “build everything” and “buy expensive.”
At Weapp we help you choose and connect the right identity solution for where you’re headed. Check out our services or get in touch and we’ll look at your needs and your expected scale.
Frequently asked questions
Why is handling your own passwords a security risk?
Because it's hard to get right and expensive to get wrong. Passwords must be stored encrypted the right way, protected against intrusion attempts, and handled according to practices that change over time. One mistake can leak your users' passwords. It's a security area where specialists invest heavy resources, and one that's rarely worth owning yourself.
When does Auth0 get expensive?
When your user base grows. The pricing model for Auth0 and similar services is often based on the number of active users, so what's cheap or free at the start can become a heavy line item once you have tens of thousands of users. Certain features organizations need also tend to sit in pricier tiers. Calculate the cost at your expected scale, not just at launch.
What is Keycloak?
Keycloak is an open identity solution you host yourself instead of buying as a service. It provides the same core functions as Auth0 – login, user management, single sign-on – without an ongoing license cost per user. The price instead is that you're responsible for operations, updates, and security, which requires expertise but gives you full control.
What are the cloud providers' built-in identity services?
The major cloud platforms have their own services for login and user management built into their ecosystem. If you're already running in a cloud, such a service can be a natural choice: it handles password security for you and integrates smoothly with everything else. The cost is often lower than a standalone service, but you become more locked into that particular platform.
Should a small product ever build its own login?
Almost never from scratch. Even a small product benefits from letting someone else carry password security, either through a service or a cloud provider's built-in solution. The exception is very special requirements that no ready-made option meets. In the normal case, a custom-built login is more risk and work than it's worth.