whereismyai
Lemma
Lemma is a free open-source PDF reader for macOS that turns mathematical references into interactive links and checks derivations.
Lemma is an open-source IDE for reading mathematics, statistics, and computer science PDFs on macOS. It parses documents locally to turn references, citations, and index entries into clickable links and previews. Readers can step through proofs like using a debugger, check handwritten LaTeX derivations with random shape values, and run Python code beside the page. It includes OCR for scanned pages, spaced repetition for notes, and exports to Markdown, Anki, Jupyter, or PDF. Users can query AI assistants like ChatGPT, Claude Code, or OpenAI, Anthropic, and Google using their own API keys with gathered contextual passages.
Lemma at a glance
- Best for: Researcher, Student
- Runs on: macOS, open source
- Pricing: Free
- Released: October 2026
- Category: AI research tool
- Website: github.com/fus3r/lemma
Key features
- Reference previewing and citation linking
- Proof step-through debugger
- LaTeX derivation checking with counterexamples
- Python code execution beside the text
- Document outline with definitions and theorems
- Spaced repetition recall schedule
- AI assistant queries with custom context and API keys
- Library search and arXiv integration
Use it for
- Reading and navigating complex mathematics textbooks
- Stepping through formal proofs line by line
- Checking written mathematical derivations
- Querying AI assistants with specific mathematical context
- Organizing research notes and exporting to Anki or Markdown
Alternatives to Lemma
- Math — Contains 722 mathematical manuscripts organized into 372 families.
- PDFMathTranslate — Translates PDF files while preserving original layouts and math formulas.
- Kelip Paper Reading — It breaks down papers across six detailed stages with local source code and image extraction.
- Paper2Agent — It enables direct interaction with research papers and automatic result reproduction.
- MathModelAgent — Automates the entire workflow from problem analysis to final paper submission.
- EasyRead，让你更舒服地读论文 — It runs locally, stays open source, and uses your own AI models for background translation.
- notebooklm-py — Automates research, content generation, and structured data export from notebooks.
- Pythos — Provides Socratic guidance and verified derivations for math and physics.
- ML News — Read concise plain-language summaries of trending arXiv machine-learning research.
- Open Math OS — It unites open frontier models, scientific compute, and data sovereignty in one workspace.
- Litmaps — Generates dynamic citation maps and watches for new relevant papers.
- Marginalia — The file stays in the browser and every answer links directly to the cited passage.
All Lemma alternatives