ChessMark

ChessMark is a local-first Chrome/Chromium extension for bookmarking chess positions from Chess.com and Lichess.

It is built for the moment when you see a position worth remembering and want to save it quickly: a missed tactic, an instructive endgame, a strange pawn structure, a blunder, a coaching question, or a position you want to analyze later.

ChessMark is a bookmarking tool, not a chess engine. It does not provide evaluations, best moves, hints, analysis lines, or gameplay assistance.

What It Does

• Detects visible chess boards on Chess.com and Lichess.
• Shows a compact preview of the detected board in the extension popup.
• Saves the current board position as a local bookmark.
• Captures a cropped screenshot of the board.
• Attempts to save FEN when available.
• Reconstructs FEN from visible board pieces when direct FEN is unavailable.
• Allows screenshot-only bookmarks when FEN cannot be captured.
• Saves visible game context such as time control and player ratings when available.
• Lets users add notes and tags while saving.
• Provides reusable quick tags for fast categorization.
• Stores all bookmarks locally in the browser.
• Provides a full library page for searching, filtering, sorting, editing, opening, copying, deleting, and exporting bookmarks.

Screenshots

Board Detection

Saved Position

Library Management

Supported Sites

ChessMark currently supports:

• Chess.com
• Lichess

The extension only activates on:

• https://www.chess.com/*
• https://lichess.org/*

Capture Flow

When the user opens the extension popup on a supported site:

1. ChessMark checks whether a board is visible.
2. The popup shows a simple status:
   • Checking
   • Board detected
   • No board
   • Error
3. If a board is detected, ChessMark shows a small board preview.
4. The user can add notes and tags.
5. The user clicks Save Position.
6. ChessMark saves a new bookmark with screenshot, source URL, timestamp, tags, notes, FEN when available, and visible game metadata when detected.

Multiple positions from the same game can be saved. Each capture creates a separate bookmark with its own ID and timestamp.

Position Data

ChessMark captures positions in this order:

1. Direct FEN from page data, URL data, attributes, scripts, or inputs when available.
2. DOM reconstruction from visible pieces and board geometry.
3. Screenshot-only fallback when FEN cannot be captured.

Bookmarks remain useful even when FEN is unavailable because the board screenshot is still saved.

Quick Tags

ChessMark includes quick tags for fast categorization:

• #tactic
• #endgame
• #mistake

Users can also type comma-separated tags such as:

opening, coach, pawn-structure, ruy-lopez, italian-game, sicilian-defense, french-defense

This makes quick tags useful for saving specific openings a player is working on, such as the Ruy Lopez, Italian Game, Sicilian Defense, or French Defense.

Typed tags are saved locally as reusable quick tags. The library also includes a quick tag preset editor for adding or removing stored tags.

Quick tags are available in:

• The popup save flow.
• The library edit view.
• The library filter dropdown.

Library Features

The ChessMark Library is a full extension page for managing saved positions.

It includes:

• Table view by default.
• Optional card view.
• Large readable board thumbnails.
• Useful generated titles instead of generic page titles.
• Notes preview.
• Visible tags on every bookmark.
• no tags placeholder when a bookmark has no tags.
• Source site label.
• Date saved.
• Time control and player rating metadata when available.
• Search by title, note, tag, FEN, source URL, source title, time control, and player metadata.
• Filter by tag.
• Filter by saved date range.
• Filter by saved my/opponent Elo ranges when rating metadata is available.
• Sort by date:
  • Newest first
  • Oldest first
• Edit notes and tags.
• Delete individual bookmarks.
• Clear all local bookmarks.
• Copy FEN.
• Open the original source URL.
• Open the saved position in an analysis board when FEN is available.
• Export all bookmarks as JSON.
• Export saved FEN positions as text.

Analysis Links

ChessMark can reopen saved FEN positions on analysis boards.

For Chess.com bookmarks, it creates:

https://www.chess.com/analysis?fen=...

For Lichess bookmarks, it creates:

https://lichess.org/analysis/standard/...

The library button is labeled Analysis for both sites. ChessMark does not analyze the position itself; it only opens the saved position on the source site's board.

Data and Privacy

ChessMark is local-first.

• No backend server.
• No account required.
• No analytics.
• No remote uploads.
• Screenshots and positions are stored locally with chrome.storage.local.
• Users can delete individual bookmarks.
• Users can clear all bookmarks.
• Users can export their data.

See ChessMark Privacy Policy. The published Chrome Web Store privacy policy URL is:

https://ctl0v0.github.io/Chessmark/privacy-policy

Fair Play Positioning

ChessMark is designed as a private bookmark and study-recall tool.

It does not include:

• Chess engines.
• Stockfish.
• Evaluation bars.
• Best move suggestions.
• Move recommendations.
• Hints.
• Blunder detection.
• Gameplay automation.
• Clock or opponent-time advice.

The intended use is saving positions for later review.

Browser Support

Current target:

• Chrome / Chromium browsers
• Manifest V3

Firefox support is not included yet.