It reads the work,
not just the answer.
Digital Red Pen — AI that grades handwritten math exams: it reads the work, not just the answer, and you make the final call.
Every exam graded in parallel — each paper read independently, at the same time — so a full class set finishes in roughly the time a single exam takes.
- Keyless grading — partial credit from the steps, no answer key needed →
- Answer key grading — per-skill breakdowns across multiple schemas →
- Exam authoring — generate a structured answer key from your master test →
- Exam variants — parallel A/B/C versions with matched keys →
- The Desk — review, override, and rule before anything ships →
- State-by-state exam retention guide →
You make the call.
The grading engine scores from the work shown. The Desk is where you review, override, and rule — and one ruling applies to every matching case in the stack. The teacher always issues the report; the machine never does it alone.
See The Desk →"Checked against my own grading, it agreed about as well as two good teachers agree with each other — and on tired nights, it was more consistent than I was."
— Zack Alexander, Co-founder
Made by teachers, grounded in cognitive neuroscience.
Zack Alexander, Co-founder — Veteran K–12 educator and former high-school math department head; taught in public and private schools; summa cum laude, UC Berkeley.
Dr. Lara Krisst, Co-founder — Cognitive neuroscientist at Caltech. She grounds Digital Red Pen in how people actually perceive and reason about their work.
Built and refined across five periods of Algebra 2 in the founder's own classroom, over a semester, before we asked any other teacher to trust it with real grades.
About us →Two tools. One workflow.
Grade handwritten exams
200 graded pages per month. Additional pages at $35 per +200-page pack. Cancel anytime.
$30/month
Apply →Archive with zero-knowledge encryption
Unlimited exams stored. Per-district retention dates. Certificate of Deletion when the window closes.
$25/year
See the Vault →Exam Vault
Keep your exams — not the cardboard box.
The Exam Vault archives your handwritten exams with zero-knowledge encryption — they're encrypted in your browser before upload, so only you can open them, not even us. Keep them for exactly as long as your district requires, pull any exam back in seconds if a grade is ever challenged, and get a Certificate of Deletion when the retention window closes.
$25 / year
Archive your exams — $25/year →Not sure how long you have to keep them? See the state-by-state retention guide →
$30/month · 200 pages included · cancel anytime
Apply for Founding Access →Built by a veteran math teacher and a Caltech cognitive neuroscientist — and refined in a real Algebra 2 classroom over a semester. → About us