Locus Problems API
A math problems API with real grading built in
Pull from hundreds of thousands of generated problems - algebra through calculus and statistics - filtered by topic, skill, and difficulty. Send a student's answer back and a computer algebra system grades it server-side, so equivalent forms count and answer keys never leave our servers.
Two calls to a graded problem
Fetch problems with GET /public/problems, render the statement, then grade the student's answer with POST /public/grade using the problem's submission token.
curl "https://api.locusmath.org/public/problems?topic=algebra_1&count=1" \
-H "x-api-key: <your-key>"What you get
- CAS grading, not string matching
- x/2, 0.5x, and x*0.5 all count. Grading runs on our servers with a computer algebra system - no answer keys in your client.
- A deep, generated corpus
- Every skill has parameterized problem templates, so you can pull fresh problems per student instead of a fixed bank.
- Filters that match how you teach
- Topic, skill, difficulty band, calculator policy, and answer type (multiple choice, widget, free response).
- A month to grade
- Every served problem stays gradeable for 31 days - assign on Friday, grade whenever students finish. Grading is free and keeps working even as our corpus updates underneath.
- Help videos on request
- Add
videos=trueand each problem links a curated explainer video for its skill.
Pricing
Start free, upgrade when your volume does. No credit card to start.
Free
$0
- 300 problems / day
- 50 requests / minute
- Grading + help videos included
- Up to 5 API keys
- No credit card required
Starter
$19/ month
- 25,000 problems / month
- 1,000 requests / minute
- Everything in Free
- 7-day money-back guarantee
- Cancel anytime
School
$79/ month
- 150,000 problems / month
- 3,000 requests / minute
- Everything in Starter
- Fits a whole school's traffic
- Cancel anytime
District / OEM
Custom
- Higher volumes + SLA
- Invoice / purchase order
- Rostering + integration help