Gander: Quick Look Preview

Press Space on a developer file and actually see what's inside.

Gander is a Quick Look extension for macOS. It turns the Space bar preview in Finder into a real viewer for the files developers open every day: Markdown with diagrams, JSON, JSONC and JSON Lines, SQLite databases, .env files, YAML, TOML, Terraform, source code, archives and more. You don't open an editor or switch apps. Select a file, press Space, and take a gander.

MARKDOWN, FULLY RENDERED • GitHub-flavoured Markdown: tables, task lists, strikethrough and autolinks • Math ($…$ and $$…$$), footnotes, GitHub alerts (Note, Tip, Important, Warning, Caution) and :emoji: shortcodes • ```mermaid blocks drawn as diagrams inside your README • Switch between Render and Raw at any time

MERMAID DIAGRAMS • .mmd and .mermaid files open as diagrams • Flowcharts, sequence, class, state, ER and XY charts, pie, mindmap, timeline, Gantt, user journey, git graph, quadrant, C4 and requirement diagrams • Diagram and Source views

JSON, JSONC AND JSON LINES • JSON opens with Tree and Raw views • JSONC (JSON with comments) works too, and so do .json files with comments such as tsconfig.json: Raw keeps every comment, and Tree still shows the data • JSONL and NDJSON show one line per record. Click a line number to expand that record as formatted JSON.

SQLITE DATABASES • .sqlite, .sqlite3 and .db files open read-only. Your database is never modified. • Structure: the columns, types, keys and indexes of every table • Content: rows table by table, up to the first 200 rows of each

.ENV FILES, SAFELY • Every value is hidden by default, and likely secrets such as passwords, tokens and API keys are flagged • Keys stay visible. Values appear only when you choose Show values.

CONFIG AND CODE • YAML, TOML, .cfg and .config files as typed, colour-coded structures • A package.json overview: name, version, scripts and dependencies • Syntax-highlighted Swift, Python, JavaScript and shell scripts • Terraform: .tf, .tfvars and .hcl files highlighted, and .tfstate as JSON • Dotfiles, files with no extension, .ini and plain text

ON EVERY PREVIEW • A copy button copies exactly what you see: code, the current JSON view, formatted Markdown, a Mermaid diagram, or a table ready for your spreadsheet. Hidden .env values stay hidden. • Code opens clean. Switch to Line numbers when you need them; copies never include them.

ARCHIVES AND MORE • The contents of ZIP (including ZIP64), XIP, tar and .tar.gz archives, listed without extracting • Text inside GZIP files • Folder contents • MIDI files, with play, pause and scrubbing

FINDER THUMBNAILS • Real thumbnails in Finder's icon, gallery and column views: rendered Markdown, colored JSON, YAML and code, Mermaid sources and archive contents • .env thumbnails show keys only, never values

PRIVATE BY DESIGN Everything happens on your Mac. There is no account, no subscription and no tracking, and nothing is uploaded. In the Gander window you can turn each preview type and each Markdown extra on or off.

Discovery signals