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Why We Built Flux

Flux TeamMarch 20, 20262 min read

Every SaaS app starts the same way. You have an idea, you’re excited, and you start building. Then reality hits.

You need authentication. Okay, that’s a week. Then your first enterprise customer wants SSO — that’s another month with SAML. Then you need feature flags to safely roll things out. Then billing. Then observability because your app is in production and you can’t see what’s happening. Then audit logs because your enterprise customer needs compliance.

Before you know it, you’ve spent more time building plumbing than building your actual product.

The 10-Vendor Problem

We’ve seen this pattern play out hundreds of times. Teams end up with a stack that looks like this:

  • Auth0 for authentication ($$$)
  • WorkOS for enterprise SSO ($$$$)
  • LaunchDarkly for feature flags ($$$$)
  • Datadog for observability ($$$$$)
  • Stripe for billing (% of revenue)
  • Sentry for error tracking ($$)
  • A hand-rolled audit log
  • A hand-rolled API key system
  • A hand-rolled rate limiter
  • …and duct tape holding it all together

The worst part? None of these tools talk to each other. Your feature flags don’t know your billing tiers. Your rate limiter doesn’t know your API keys. Your audit logs don’t know your tenants.

You end up writing thousands of lines of glue code to connect the disconnected.

Everything Connects

Flux takes a fundamentally different approach. Instead of being “another tool in the stack,” we built a unified platform where every capability is aware of every other.

Feature flags that know your billing tiers. Rate limiting that knows your API keys. Audit logs that know your tenants. Auth that knows your entitlements.

One import. One dashboard. One bill.

Built in Rust

We chose Rust for the hot path because your infrastructure should never be the bottleneck. Flux processes auth decisions, flag evaluations, and rate limit checks with single-digit microsecond latency.

But we’re not a “Rust-only” platform. We have SDKs for every major language and framework. Rust just happens to be what powers the engine under the hood — and yes, if you’re building in Rust, the experience is especially good.

What’s Next

We’re in early access right now. The platform handles auth, billing, feature flags, observability, secrets management, and more — with background jobs, webhooks, and API key management coming soon.

If you’re building a SaaS app and you’re tired of building plumbing, get started with Flux.