We invented Spaced Repetition (40 years ago)
Now we give you its best algorithm (in API)
Integrate the legendary SuperMemo Spaced Repetition algorithm into your own platform. Scientifically optimize memory retention with just a few lines of code.
POST /algorithm/review
{
"ext_learner_id": 1,
"ext_collection_id": 1,
"ext_item_id": 1,
"algorithm_type": "SM20",
"grade": 0,
"review_date": ""
}
// Returns interval: 1
The Science of Persistence.
From Dr. Piotr Wozniak's first observations in 1985 to the world's most sophisticated memory model.
1985: The Discovery
The initial mathematical model for the "Forgetting Curve" was established, moving memory from mystery to engineering.
SM-20: Peak Precision
Decades of refinement led to SM-20, an algorithm that calculates the optimal moment for review with the highest recall probability.
What is Spaced Repetition?
Spaced repetition is a learning method based on reviewing information at carefully timed intervals so you remember more and forget less. It did not appear out of nowhere as a trendy study hack.
Its modern form grew out of decades of memory research, but the breakthrough came with SuperMemo in the 1980s, when Piotr Woźniak began turning the problem of forgetting into a practical learning system.
With more than 30 years of history behind it, spaced repetition is still evolving, and the algorithm continues to be refined and improved. The story is fuller, more surprising, and far more nuanced than the simplified versions repeated online today. Read the full article and discover how spaced repetition really evolved: The True History of Spaced Repetition.
Precision of review intrerval: +99%
What is SuperMemo API?
SuperMemo API provides access to the legendary spaced repetition algorithm that has powered effective learning for decades. It enables developers to integrate intelligent review scheduling into their applications, helping users remember more by optimizing when and what they review.
With simple API calls, you can add proven memory science to any learning product - without building complex logic from scratch.
Simple. Systematic. Scalable.
The architecture of memory, reduced to three logical steps.
Input Data
Send the item ID and the user interactions.
API Computes
The SM-20 engine calculates the precise interval for the next review.
Feedback Loop
Update the schedule based on real-world recall performance.
speed Limits & Implementation
Start Building Instantly.
Our public beta allows for rapid prototyping without limits.
- ● 10,000 Requests / Month
- ● 50 Requests / Minute
- ● 10 Active Projects
Create an account
Sign up and be among the first to use it.
Generate key
Create a project-scoped API key.
Engineered for every learning niche.
Language Apps
Master vocabulary with scientifically timed repetitions.
EdTech
Embed deep learning into digital textbooks and courses.
Quizzes
Transform trivia into permanent knowledge structures.
Corporate
Drastically reduce retraining costs through knowledge retention.
key Key Concepts
The Wallet
Manage your API credits, usage logs, and transactional history in a unified interface.
Playground
Test the SM-20 algorithm in real-time with our metrics visualiser.
Projects
Isolate data for multiple projects.
The Road Ahead.
Incremental Reading
Native API support for breaking down long-form content into manageable repetition units.
The Algorithm Arena
Real-time metrics comparing SM-20 against FSRS and other emerging models.
More algorithms
Expand beyond SM-20 with additional learning algorithms tailored to different use cases and learning styles.
Pricing & transactions
Flexible pricing plans and seamless billing to support developers and scale with your product.
First Beta Access
WE ARE HEREInitial public rollout for registered developers and early partners.
Predictable Pricing
Simple billing that scales as your user base grows.
Free
For hobbyists and prototypes.
- check 1,000 API calls/mo
- check Community Support
- check Standard SM-2 Algorithm
Dev
For growing platforms.
- check 100,000 API calls/mo
- check SM-20 Algorithm
- check Priority Email Support
- check Advanced Analytics
Scale
For enterprise operations.
- check Unlimited API calls
- check Custom Algorithm Tuning
- check Dedicated Account Manager
- check SLA Guarantees