Free to build. Memberships when you want more AI help.
You can go all the way from finding a project to finishing it without paying. BEI Plus and BEI Scientist add monthly AI credits and member features, and you can also buy prepaid credits on their own.
Free
Free
Start building and experimenting.
- 20 free AI credits, once
- Explore and search every experiment
- Create, save and edit your own projects
- The full project journey: idea to conclusion
- Measurements, trials, calculations and graphs
- Community, comments and public profile
- Science fair planning and display board basics
- Buy more AI credits any time
Most popular
BEI Plus
Not available here yet
Build more, get more AI guidance.
- 50 AI credits every month
- Everything in Free
- Project templates and structured starting points
- Project journal and build log
- Enhanced project documentation
- Enhanced portfolio with a featured project
- Downloadable project summary
- Enhanced science fair report and judge practice
BEI Scientist
Not available here yet
For serious projects, research and science fairs.
- 150 AI credits every month
- Everything in BEI Plus
- Advanced project review: strengths, gaps, next steps
- Advanced data and experiment analysis
- AI judge simulation and presentation coaching
- Photo and file understanding for your project evidence
- Portfolio and report export
Monthly credits refresh each month and a limited amount carries over. Credits you buy separately never expire. Cancel any time — you keep the month you paid for.
AI credits
20 free
Or buy prepaid credits any time
- 20 free AI credits on every new account
- One credit per normal AI answer
- STEM Mentor, project help, data help and science fair coaching
- Credits never expire
- Buy more only when you want to — with or without a membership
- Failed or blocked AI requests are always free
Creator
Free to publish
Earn from premium projects
- Create and publish projects
- Upload images and structured instructions
- Creator profile and basic analytics
- Reviews, community results and remixes
- Set your own price on premium projects
- Keep the majority of every sale
Credit packages
Loading prices…
- One credit per normal AI answer
- Credits never expire
- No subscription and no auto top-up
- Failed or blocked AI requests are always free
Want your balance and past purchases? Open your AI credits page.
Educator Coming soon
For teachers and homeschool groups: classroom projects, student management, assignment templates, class analytics and shared project collections.
Creator marketplace fees
Sell premium projects for free — one flat platform fee on each sale.
Every creator
20% fee
You keep 80% — USD $8 on a USD $10 sale.
What AI credits pay for
Credits are only spent when an AI feature actually answers you. Everything else — building, measuring, graphing, publishing and the science fair pack — is free.
STEM Mentor
Ask questions and get guided help while you plan an experiment.
Project help
Ask about a specific project you are building.
Data help
Talk through the numbers you actually recorded.
Project generator
Turn an idea into a structured project draft you can edit.
Science fair coaching
Readiness feedback, board planning and judge practice.
Reflection help
Draft a conclusion grounded in your own results.
How money works here
- Do I need to pay to build projects?
- No. Discovering, starting, building, recording data and finishing a project are all free on every account.
- What is a premium project?
- A creator can choose to charge for access to their project template and instructions. The price is always shown on the card and the project page — never hidden.
- How do creators get paid?
- Creators keep 80% of every premium sale (20% platform fee). The fee covers payment processing, hosting, moderation and support. Earnings are held briefly in case of refunds, then paid out to the creator's connected payout account.
- Do AI credits expire?
- No. Credits stay on your account until you use them. One credit is spent per successful AI answer; failed or blocked requests cost nothing.
- Does the AI do the project for my child?
- No. Every measurement is entered by the builder and all statistics are calculated from those numbers. The assistant only explains concepts and asks guiding questions.