tiun

Shipping an AI product usually means stitching together an auth provider, a payments processor, a customer database and an analytics tool, then writing the webhook glue that keeps all four agreeing on who a user is and what they have paid for. tiun collapses that stack into a single backend so the four stay in sync by construction rather than by code you maintain.

Authentication covers sign-up, login, logout, user profiles, multi-factor auth over SMS or email, and social SSO — the login screen and account pages are drop-in components rather than flows you build. Payments handles one-time purchases, subscriptions and usage-based billing metered down to the event, so per-token, per-API-call, per-compute or per-storage pricing is a configuration choice instead of a metering service you run. Pre-built checkout components ship with it, and tiun acts as merchant of record, taking on sales-tax and VAT registration and remittance.

The customer database is the piece that makes the rest cohere: one record per user carrying subscription state, event and session logs, transactional email, invoices and data APIs, so support questions like "what plan is this person on and what did they just do" are one lookup. AI analytics sits on top, reporting across signups, payments and product usage, and answering pricing questions in natural language — an add-on from $17/month.

Two details make it specifically an AI-era backend rather than a general SaaS one. Usage-based billing is designed for token and inference metering, where the cost of goods moves per request. And the platform exposes an MCP interface, so an agent can query customers, subscriptions and revenue directly.

Transaction pricing is quoted at 2.9% + $0.30, which tiun positions below Polar, Lemon Squeezy and Paddle. There is a free tier to start. Best suited to indie developers and small teams launching paid AI products who would rather not run four vendors to do it.