Open your material
Write your own notes or bring in the PDF you are studying, including its text and diagrams.
Private betaAccess details
Notes, PDFs, and diagrams
Clarity begins with a single circle.
Clean up rough notes, circle the exact text or diagram you do not understand, or turn dense material into visual models. Penombra helps you see the same idea from more than one angle.
Works with notes and PDFs Your notes stay yours
Three ways to find clarity
From the page to the point.
Watch Penombra clean up rough notes, explain a circled passage, and make sense of a selected diagram.
Rough handwriting, organizedClean notes
Made for the notes you take inclassthe librarythe labeveryday life
Point to what you mean
Help for the exact part that is confusing.
There is no need to copy a paragraph into another app or describe which piece of a diagram you mean. Circle it where it already lives.
Circle what you mean
Draw around a sentence, label, chart, or diagram area just as you would on paper.
Get a clear explanation
Penombra uses the selection and surrounding page to explain that exact part in context.
Ideas in every form
Read it. See it. Understand it.
Clean up rough notes
Turn quick handwriting and scattered thoughts into a clear, useful outline.
Explain your notes
Ask about something you wrote and get a plain-language explanation in context.
Circle text in PDFs
Draw around any confusing passage and have Penombra explain exactly what it means.
Understand diagrams
Circle a chart, label, or section of a diagram and get that specific part broken down.
Turn text into visual models
Transform dense passages into diagrams, timelines, comparisons, and other useful representations—so you can understand the same idea from more than one angle.
All notes
Cell biologyWhat is mitosis?Updated todayEnergy and the cellReadingThe shape of a questionMemory & learning
Everything has a place
Your notes and source material, together.
Keep handwritten notes beside the PDFs, figures, and passages they came from. Clean up what you captured, then circle anything you want explained.
Explore the notebookYour work stays yours
A private place for unfinished thoughts.
Penombra is designed around ownership, control, and clarity. Your pages are not a public feed, and assistance should always feel like a choice.
Your notebookPrivate by default
Questions, answered
Before you open a page.
What is Penombra?+
Penombra is an AI notebook for understanding your own notes and the material you read. It can clean up rough notes, explain the exact area you circle in a PDF, and reshape dense text as diagrams, models, timelines, and other visual forms.
Can I use it without a tablet?+
Yes. Penombra works in a browser on desktop, tablet, and mobile. Native iOS and Android apps are part of the product roadmap.
What can I import?+
You can import PDFs and common image formats, then write on them and circle the exact text or diagram you want help with.
Does Penombra train on my notes?+
Your notes belong to you. Privacy controls let you choose what can be used for assistance, and your content stays behind your account.
How does the page assistant work?+
Circle a passage, label, or part of a diagram. Penombra uses the selected area and the surrounding page for context, then explains it beside the source. You can also ask it to clean up or explain your own notes.
Is there a free plan?+
The web notebook is available to try. Paid plans will support storage, audio, collaboration, and higher usage limits as those features ship.
The next thought starts here
Start with one page.
Use Penombra on the web today. iOS and Android apps are on the way.
Use Penombra on the web iOS · Android · Web