Runs on Complement
Free
No time limit and no device limit.
- Spaced repetition with FSRS
- Anki import
- The editor and Studio
- Stats and widgets
- Publishing and sharing decks
Complement is free.
You pay only for what costs money.
Studying, your decks, and everything around them cost us very little to run, so they’re free on every device. AI and a few services on our servers cost money each time they run. Here’s where each one runs, and who pays.
Where each part of Complement runs, and who pays for it
Your devicesWebiPhone and iPad, coming soonas many as you like
Runs on your OpenRouter account
At cost
You pay OpenRouter per request, at the model’s price.
- Chat and explanations
- Definitions
- Board-style practice questions
- Card writing and deck generation
Your first $1 of AI is on us.
Why your own keyRuns on services we pay for
The Complement subscription, $4 a month
or $40 a year. Optional, and you can cancel anytime.
- Semantic search
- Related cards and duplicate checks
- Fact checks
- Web search in chat, and image search
- Image exhibits in practice questions
Prices in USD. The final price, including any tax, is confirmed at checkout.
Why AI runs on
your own key.
A plan that bundles AI has to guess how much everyone will use, then charge for the heaviest month. With your own OpenRouter account there’s nothing to guess. You pay for the requests you make, and nothing in the weeks you don’t.
- No markup
- Requests are billed by OpenRouter at the provider’s price. Complement adds nothing on top.
- Encrypted, never plain text
- Your key is encrypted before it’s stored, and Settings only ever shows its last four characters. Disconnect it there, or revoke it at OpenRouter, whenever you like.
- Connect once
- Connect on the web once, and the same account pays for AI everywhere you sign in.
- Every cent visible
- OpenRouter lists what each request cost, and Settings shows your AI spend this month, by feature.
Complement
Sends your requests on your key
Your key, encrypted
OpenRouter
Bills your balance at each model’s price
OpenAI
Anthropic
Google
xAI
DeepSeek
Moonshot
Why there’s a subscription.
Complement started in medical school, and the people closest to us study with it every day. The subscription is how it pays its own way: it covers the servers, and the services that cost us each time they run.
It will never stand between you and your reviews. Learning well is becoming one of the most important skills a person can have, and we want the tool for it to be open to anyone, and to last.
Where a feature sits follows what it costs to run. When a service gets cheaper, its feature can move to free. The rule itself won’t change.
Questions
Do I need an OpenRouter account to start?
No. Everything free works without one, and your first $1 of AI runs on Complement’s key. When it’s used up, connect OpenRouter from Settings: you sign in there and approve Complement, with no key to copy.
How much will AI cost me?
It depends on the model and how much you use it. Model providers price per token, OpenRouter shows the cost of every request, and Settings shows what you’ve spent this month.
Why isn’t semantic search on my own key?
Because it doesn’t run on a language model. Indexing your cards for search, web search, and image search run on services Complement pays for each time they’re used. That’s what the subscription covers.
Is there a free trial of the subscription?
No. Everything free stays free with no time limit, so you can use Complement for as long as you like before deciding.
What happens if I cancel?
You keep everything that’s free, and cards that were already indexed stay searchable. New and edited cards stop being indexed. Cancel anytime from Settings; billing runs through Stripe.
Is there an iPhone or iPad app?
It’s in testing now and coming soon. It will be free, like the web, and a subscription bought on the web applies there too.
How does yearly billing work?
You’re billed $40 once a year, which works out to $3.33 a month. Prices are shown in your local currency where we can, and confirmed at checkout.