I built a tool to check if you're overpaying for AI subscriptions

got my credit card statement last month and actually looked at it for once.

turns out i was paying $120/month across 6 AI subscriptions. ChatGPT Plus, Claude Pro, Cursor, Copilot, Perplexity, Midjourney. each one was "just $20" so i never added them up.

the dumb part is three of them (ChatGPT, Claude, Perplexity) do basically the same thing. same product in different packaging lol.

so i built a dumb page to check: https://aicosts.bmaster.cn

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it does two things:

1. subscription checker — checkboxes for ~50 AI tools with real prices. check what you use, it shows monthly/yearly/weekly/daily totals. prices are editable since regional pricing varies.

2. API cost comparison — pulls live per-token pricing from OpenRouter for 300+ models. you enter your usage (prompts/day, avg tokens) and it estimates your monthly API cost, so you can compare "Claude Pro $20/mo" against "Claude API at my actual usage = $X/mo."

for me that number was $14/mo on API vs $20 for Pro. dropped two overlapping subscriptions, cut my stack to $50/month.

tech stuff:

• vanilla js, no framework, no build step
• the whole thing is one html file
• no backend, no signup, no tracking
• OpenRouter API is called directly from the browser (they support CORS)
• subscription prices are hardcoded but editable in the UI
• model pricing comes from OpenRouter's /models endpoint

i'm not a frontend person so the code is probably ugly but it works.

anyone else have a stack that crept up on them? curious what other people are paying.