SaaS

Offer an AI tool free to users with AI accounts

Offer an AI tool free to users who connect their own AI account (their own API key, so they pay the AI company directly), and charge a monthly fee to those who use yours.

The hard part: making the paid tier feel worth it when the free own-key path already works.

Setup 1 weekRuns $35/moYour time A weekly check-inNeeds ClaudeSupabaseVercelStripe

Who pays

Users who don't want to manage their own API key pay a monthly subscription. Users with their own key pay nothing.

How to build it

  1. Build the backend with AI access

    Build the app or extension backend on Vercel, and call the OpenAI, Anthropic, or xAI API with whichever key the user's plan uses.

  2. Store keys safely and track usage

    Store user API keys encrypted in Supabase, and log each user's usage there.

  3. Charge for using your key

    Set up a Stripe subscription for the plan that uses your key, and only send requests through your key for users with an active subscription.

  4. Cap free trial usage

    Put hard usage caps on any free trial that runs on your key or another paid API, so trial users can't run up your bill.

  5. Make sure each plan profits

    Check your API costs per paying user in Supabase against what Stripe collects, and raise the price or lower the caps if a plan loses money.

Sources on X

  • cultureofcode · May 21, 2025

    This is a secondhand account of another builder. When the API came out, the builder offered two options: free with your own key, or $16/month with the builder's key, a price reported as of 2025-05-21. Per the account, the product reached $4K MRR within 30 days, doubled a month later, and was at $20K/month at the time of the post.

  • nickbakeddesign · Sep 29, 2026

    A free Chrome extension that cross-posts X posts to LinkedIn. Its tone customization uses Claude with the user's own keys. It shows the own-key free tier in practice. No revenue is stated.

  • marclou · Sep 4, 2026

    Marc Lou says the product Stalkr reached $116 MRR but is the first SaaS he has built that loses money, because of its free trial: the data is expensive, especially X posts. As of 2026-09-04, the free trial cap was reported cut from 100 mentions to 10.

Ideas are curated from public posts and untested by us. Read the full note.