How We Dropped Vue.js for Reliability: The Story of an Authentication Module

Context: Single Sign-On at Scale

Our team was brought into a large project to take responsibility for its single sign-on (SSO) module—the central entry point for every other service in the ecosystem.

The project’s stack:

• Backend: Laravel
• Frontend: Vue.js
• Database: MySQL
• Message queues: RabbitMQ
• Authentication: SAML

Our role seemed straightforward: provide seamless access to all services through a single authentication module. Everything worked—until it didn’t.

The Problem: Authentication Loops

We began receiving recurring incident reports: when users tried to sign in, the authentication pages would get stuck in a loop, preventing them from logging in.

Users reported:

• Endless redirects.
• Getting stuck on the login screen.
• Being unable to complete authentication.

At first, it looked like an isolated bug. But as adoption grew, so did the number of complaints. We started investigating in depth.

We expanded our logging, collected frontend and backend data, and analyzed request patterns. What we found was far from obvious.

Some users were working on older devices with outdated browsers. That alone was not necessarily a problem—many services support legacy environments. However, these users also had corporate security software installed with specific configurations mandated by their company’s security team.

Here is how the issue unfolded:

1. The browser loaded the Vue.js authentication page.
2. The corporate security software analyzed the traffic and the page’s behavior.
3. Certain Vue.js behaviors—dynamic loading, asynchronous requests, and DOM updates—caused the software to misinterpret the activity.
4. In response, it began blocking or reissuing requests.
5. Those requests kept reaching the server, over and over again.

The result: hundreds of users running this software were effectively launching a distributed denial-of-service attack against our authentication service—not maliciously, but because their security software was reacting incorrectly.

The issue was not simply the volume of traffic. It was a conflict between a modern JavaScript frontend and client-side corporate security systems.

The Solution: Simplicity Over Modernity

We made an unpopular decision, but the only right one for this situation: rebuild the authentication service using the simplest possible stack.

What we used:

• HTML: static markup, with no dynamic generation.
• CSS: plain styles, with no frameworks or preprocessors.
• Vanilla JavaScript: no libraries, frameworks, or bundlers.

What we removed:

• Vue.js and its entire ecosystem.
• Asynchronous component loading.
• SPA routing.
• Unnecessary XHR requests during authentication.

The guiding principle was simple: the authentication page should be straightforward enough that no browser or security system would find its behavior suspicious.

After the migration:

• There were no further incidents related to our service’s operation.
• There were no conflicts with corporate security software.
• There were no authentication loops or endless redirects.
• The load on the authentication server dropped substantially.

Functionality remained intact: users could still access every service in the ecosystem through single sign-on.

What We Learned

1. Modern Is Not Always Right

Vue.js, React, and other frameworks work well for products whose users have modern browsers. But for a critical authentication module in a corporate environment, predictability and compatibility matter more than development speed.

2. Users Aren’t Always at Fault

When complaints come from people using older devices, it is easy to blame their setup. But the real cause often lies deeper: interactions between legacy browsers and modern frontends can create conflicts that never appear in a test environment.

3. Logging Makes Diagnosis Possible

Without detailed logging, we would never have seen that the problem was not just traffic volume, but the request pattern itself. The logs showed that the requests were coming from real users running security software—not attackers.

4. A Step Back Can Help

Replacing Vue.js with vanilla JavaScript looked like a step backward. In practice, it was an engineering decision driven by real-world operating conditions rather than trends.

Conclusion

This story is not about Vue.js being bad. It is about making architectural decisions based on context, not trends.

For an authentication module in a large corporate ecosystem, simplicity proved more reliable than a modern frontend stack. This was one of those cases where “simpler” really did mean “better.”