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User Guide

Welcome! This guide takes you from installing Lexicon to running a well-organized, interlinked knowledge dictionary.

What is Lexicon?

Lexicon is a free, open-source application for structured learning and technical note-taking. Instead of a folder full of loose notes, you build a personal dictionary of items, organized into groups, enriched with metadata, and connected by typed links that form a concept graph.

Data is stored locally in a SQLite file, with optional attachments in an adjacent directory — no account, no cloud, no telemetry. You own your knowledge.

There are three clients over one dictionary: the Qt desktop application, which opens the database file directly, and a web client and a native Android app, which talk to LexiconServer next to that same file. What you write in one shows up in the others — including reviews, cards, alarms, the Inbox and the shared Board. Desktop and web additionally provide Mass Insert for creating a batch in one recoverable worksheet.

Core concepts

Five ideas are enough to understand the whole application:

Review brings due items back on a schedule, while cards let you quiz yourself on specific questions. Alarms ring in every client, the Inbox catches an idea before it is gone, and named shared Boards keep living Markdown overviews close at hand.

Quick start checklist

1. Install and launch Lexicon. The database file is created automatically on first start.
2. Organize your groups via Manage → Groups.... A Default group is ready when you start.
3. Add a few items with the Add button and fill in their titles.
4. Use Mass Insert for a batch — choose one Group, an optional Type and fill several rows safely.
5. Write content in Markdown in the Content tab and watch the live preview.
6. Connect related items with typed links to grow your concept graph.
7. Review what you wrote — the items due now, one card at a time.
8. Quiz yourself with cards — questions about an item or its linked neighborhood.
9. Set up a backup habit — copy the database and its adjacent blobs directory, or let the server back it up for you.

Guide chapters

Study Plan schedules books, courses and practice by weekday and shows today’s target.