LocusAPI
Locus Problems API

Simple, flat pricing

Every plan gets the full corpus and server-side CAS grading. Paid plans raise your request pool - nothing is paywalled beyond volume.

Free

$0
  • 300 problems / day
  • 50 requests / minute
  • Grading + help videos included
  • Up to 5 API keys
  • No credit card required
Get an API key

Starter

$19/ month
  • 25,000 problems / month
  • 1,000 requests / minute
  • Everything in Free
  • 7-day money-back guarantee
  • Cancel anytime
Subscribe

School

$79/ month
  • 150,000 problems / month
  • 3,000 requests / minute
  • Everything in Starter
  • Fits a whole school's traffic
  • Cancel anytime
Subscribe

District / OEM

Custom
  • Higher volumes + SLA
  • Invoice / purchase order
  • Rostering + integration help
Contact us
How quotas count
One request = one problem served, with its grade and optional help video included; a batch of 5 problems counts 5, and listing topics is free. Served problems stay gradeable for 31 days. Quotas are per account, shared across your keys. Free is a daily quota; paid plans are a calendar-month (UTC) pool.
Hard caps, no surprise bills
At the cap, requests return 429 until the window resets. You are never billed for overage.
Billing terms
Monthly billing through Stripe, cancel anytime from the dashboard, 7-day money-back guarantee on your first payment.
Upgrades
Moving from Starter to School? Subscribe to School and the remaining Starter payment is refunded automatically.

Need more than 150,000 requests/month, invoicing, or integration help? Talk to us about a District plan.