Why three tools that "work together" still break your business
Your MVP is live, users are signing up and the first payments are coming in. But then something breaks silently.
A user upgrades their plan. The payment goes through in Stripe. But the webhook fires at the wrong moment, your database hasn't updated yet, and the user is still on the free tier. They email support, but you spend 40 minutes debugging an event log. You find the issue, fix it manually, and document it as a known edge case.
Two weeks later, it happens again.
This is not a Stripe problem it's not even an auth problem, it's not a database problem. It's what happens when three systems that were never designed to talk to each other are forced to share state about the most important thing in your business: whether a paying customer has access to what they paid for.
The Stack Everyone Builds (And Maintains Forever)
The standard early-stage SaaS setup looks something like this: Clerk or Auth0 for authentication. Stripe for payments and subscriptions. A Postgres database to store users and their entitlements. Three separate dashboards. Three separate API keys. Three separate billing accounts.
It should work perfectly, but in reality it becomes a synchronization problem that compounds over time.
Every Stripe webhook can mean plenty of different things: a new subscription, a renewal, a failed charge, a cancellation, a refund, a dispute. Each event needs to update your database, each update determines what a user can access and if any of it fails, you won't know until someone complains.
Developers who have shipped more than one SaaS product know this problem by heart. The auth setup takes a day, the billing integration takes a week and the entitlement logic (making sure the right users have access to the right features at the right time) takes another week and produces code that nobody wants to maintain.
And that's before dark mode, localisation, or a second pricing tier.
What "Three Lines of Code" Actually Means
tiun is a backend platform built by our team. We spent time interviewing 150+ early-stage founders before writing a single line of code. What we heard consistently, was the same story: the infrastructure wasn't the interesting part of building a product. It was the part that kept breaking.
Our answer was to build auth, payments, and customer data as a single unified system. Not three tools with integrations between them, but one stack where these layers share the same data model from the start.
In reality this means:
Authentication ships with sign-up, login, logout, MFA via SMS and email, Social SSO, a user button component, and a profile management overlay. All ready to drop into your app without custom UI work.
Payments covers one-time purchases, subscriptions, and usage-based billing. tiun acts as the Merchant of Record, which means tax compliance and chargeback handling are included. The billing fee is 0.7% on top of standard card processing, lower than Paddle's equivalent. Checkout components are pre-built overlays, so users never leave your page.
Customer database is where the system earns its differentiation. Every user's subscription status, transaction history, and session data lives in the same place as their auth record. When a subscription renews, there's no webhook to handle, no sync to maintain, no edge case to document. The state is always consistent because there's only one place it lives.
Analytics logs every login, purchase, and product interaction at the individual user level, but per-profile behaviour that tells you what features drive retention and what pricing tiers convert.
The Entitlement Problem, Solved
Entitlements are the quiet killer of SaaS infrastructure. The concept is simple: users who are on the Pro plan should have access to Pro features. Users who cancel should lose that access. Users who upgrade mid-cycle should gain it immediately.
The implementation is where complexity hides. Entitlement state sits between your auth system (who is this user?) and your billing system (what have they paid for?). When those systems are separate, they can fall out of sync. A failed webhook, a delayed event, a database write that happens out of order. Any of these can result in a paying customer losing access, or a churned customer retaining it.
tiun eliminates this class of bug structurally. Because auth and billing share the same data model, entitlement state is never derived from syncing two systems. It's a property of a single record. There's nothing to sync because there's only one source of truth.
Who tiun Is Built For
The target user is a founder, indie developer, or small engineering team shipping a SaaS or AI product who wants to reach paying customers quickly without building and maintaining custom backend infrastructure.
The integration model reflects this: tiun exposes an MCP server, meaning AI coding agents like Cursor or Claude Code can install and wire the entire backend with a single command (gh skill install tiun-app/skills). No manual configuration. The agent handles the integration; the developer reviews the result.
This positions tiun at an interesting intersection: it's infrastructure for the AI-native development era, where the bottleneck is no longer "can I write this code?" but "how much boilerplate do I have to configure before I can ship something real?"
How It Compares
The honest competitive landscape includes Stripe (payments only, no auth, no database), Clerk (auth only, no payments), Paddle and Polar.sh (closer comparisons - both offer Merchant of Record billing with some auth integration, but neither unifies the customer database layer in the same way).
tiun's differentiator is the unified data model. Every competitor in this space is either a payments tool that added auth, or an auth tool that added billing. tiun's architecture was designed around the entitlement problem first, with auth and payments as the input layers.
The pricing is also worth noting. At 3.6% + $0.30 all-in (0.7% billing fee + standard card processing), it's meaningfully cheaper than Paddle's equivalent and includes Merchant of Record status, tax compliance, and chargebacks.
Building a product is hard enough. The infrastructure underneath it shouldn't be where the interesting problems live.
tiun is available at tiun.io. Integration takes one command. Tax compliance, Merchant of Record handling, and chargeback resolution are included.
Top comments (2)
Hey Nikolaos! Thanks for presenting the problem so clearly.
But why would I choose tiun over Stripe + Clerk/Auth0 + Supabase/Postgres? What do I actually gain beyond less setup?
At what stage does a unified stack become a better choice than assembling the backend myself with established tools?
Since tiun’s main differentiator is the unified auth + billing + entitlement data model, how do you handle late, failed, or out-of-order payment events?