QuickestLook

Beautiful previews, any file.

A Quick Look extension for macOS that turns Space-bar previews into something worth looking at. Source code with proper syntax highlighting, configs you can actually read, notebooks that render their outputs, CSVs as real tables, archives as a tree. Privacy-first — runs entirely on your Mac.

View supported files Privacy

Features

What QuickestLook does

Press Space on a file in Finder. Get a preview that respects the content.

Beautiful source previews

Syntax highlighting for dozens of languages — Swift, Python, TypeScript, Rust, Go, and more. The kind of preview you’d expect from a real editor.

Modern macOS 26 design

Two themes built for macOS — Calm for quiet reading, Vivid for high contrast. Designed to feel native.

Privacy-first

Secret masking is on by default. API keys, tokens, and passwords in .env and config files are hidden until you choose otherwise.

Notebooks rendered properly

Jupyter .ipynb previews show markdown cells, code, and output — including embedded images.

CSV and TSV as tables

Tabular data renders as an actual table, not a wall of comma-separated text.

Zip archives as a tree

See what’s inside a .zip without unzipping it.

Supported files

What you can preview

Grouped by category. The list keeps growing as new renderers ship.

Source code

.swift.m.mm.c.h.cpp.cc.cxx.hpp.hh.hxx.py.rb.sh.bash.zsh.php.js.mjs.cjs.ts.tsx.jsx.rs.go.kt.kts.dart.graphql.gql.css.scss.sass.less.vue.svelteMakefile.mk

Markdown & docs

.md.markdown.qmd.rmd

Data & config

.json.jsonl.ndjson.yaml.yml.toml.ini.conf.cnf.cfg.properties.editorconfig.npmrc.yarnrc.nvmrc.gitignore.dockerignore.npmignore.gitattributes

Apple ecosystem

.plist.entitlements.xcconfig.strings.xcstrings

Logs & environment

.log.env.env.local.env.production

Secrets in environment files are masked by default.

Notebooks

.ipynb

Tabular

.csv.tsv

Web

.html.htm.xhtml.xml.svg

Lock & manifest

package-lock.jsonyarn.lockCargo.lockGemfile.lockPodfile.lockPackage.resolved

Disk images

.dmg

Metadata, signature info.

Subtitles

.srt.vtt.ttml

SQL

.sql

Protocol Buffers

.proto

Settings

Settings & customization

Tune QuickestLook to your preferences. Everything is stored on your Mac.

Theme: Choose Calm for quiet reading, or Vivid for high contrast.
Font: SF Mono by default, or any installed monospace font.
Font size: Set the size that’s comfortable for your eyes and your display.
Per-renderer enable / disable: Turn off renderers you don’t need so QuickestLook stays out of the way.
Maximum file size: Cap how much of a file each renderer reads — useful for huge logs.
Reveal secrets: Off by default. Toggle on temporarily when you actually need to see the value.
Custom CSS file: Advanced: drop in your own stylesheet to fully theme the previews.

Troubleshooting

The two issues people run into most often, with the fix.

I press Space on a file and don’t see QuickestLook’s preview.

macOS routes each file type to a single Quick Look extension based on which app is registered as the handler for that file type. If you have another app installed that claims a file type QuickestLook also supports — for example, BBEdit claiming .sql, or Warp claiming .toml, or Numbers claiming .csv — that other app wins the routing, and QuickestLook is not invoked. This is a macOS limitation that no Quick Look extension can bypass on its own.

The fix takes ten seconds:

In Finder, right-click any file of the affected type.
Choose Get Info.
In the Open with: section, change the app to QuickestLook. (If QuickestLook is not in the list, choose Other… and select QuickestLook from /Applications.)
Click Change All… and confirm.

macOS will now route Quick Look for that file type to QuickestLook on your Mac.

Common conflicts to know about: .csv → Numbers (if installed) · .toml, .cjs → Warp (if installed) · .sql, .rs → BBEdit (if installed) · .ts → macOS treats as MPEG-2 video by default.

QuickestLook’s extension is installed but doesn’t show up.

Quit and relaunch QuickestLook once from /Applications.
Open System Settings → General → Login Items & Extensions → Extensions → Quick Look.
Make sure QuickestLook Preview and QuickestLook Thumbnail are both enabled.
If they were already enabled, toggle them off and on again. macOS occasionally needs this nudge after OS updates.

Privacy

Privacy Policy

Effective Date: 1 May 2026 · Last Updated: 1 May 2026

QuickestLook is designed to leak nothing. The short version: it does not collect, transmit, or share any data from your usage. The sections below explain what that means in practice.

1. Information We Collect

App usage: none. QuickestLook does not collect analytics, telemetry, crash reports, or any other usage data.

Files: QuickestLook reads only the file you explicitly preview in Finder, processes it locally, and discards the data when the preview is dismissed.

Preferences: Your settings (theme, font, font size, per-renderer enable/disable, maximum file size per renderer, custom CSS path, reveal-secrets toggle) are stored locally on your Mac in standard macOS preferences. These never leave your device.

Purchases: Optional supporter purchases are processed by Apple through the Mac App Store. Apple may share aggregate purchase metadata (country, app name) with the developer; Apple never shares your name, email, or payment details.

2. How We Use Information

QuickestLook does not have access to any information outside of files you explicitly preview. Local preferences are used only to render previews to your taste — font, theme, which renderers run, and so on. There is no other use.

3. Data Storage and Transmission

QuickestLook stores all data locally on your Mac. There is no remote server for your files, and no analytics or telemetry are transmitted at any time.

The single exception is a project-status check: QuickestLook checks once per launch whether the project is still maintained by fetching helaia.com/quickestlook/status. No personal data is sent.

4. Third-Party Services

QuickestLook does not integrate with any third-party services. The only third party in the loop is Apple, which handles distribution and (optional) purchases through the Mac App Store. Apple’s handling of that data is governed by Apple’s privacy policy.

5. Secret Masking

When previewing config files (e.g. .env, .xcconfig), QuickestLook automatically detects values that look like secrets — API keys, tokens, passwords — and masks them by default. This protection runs entirely locally; nothing is transmitted. Masking can be toggled in QuickestLook’s settings.

6. Children’s Privacy

QuickestLook does not collect any data from any user, including children. It is suitable for users of any age.

7. Your Rights

Because QuickestLook does not collect or transmit data, there is no personal data for Helaia to access, correct, or delete on your behalf. Your local preferences can be reset at any time from QuickestLook’s settings, or by removing the app’s preference file from your Mac.

8. Changes to This Policy

If this privacy policy changes, the updated version will be published at helaia.com/tools/quickestlook#privacy. The “Last Updated” date above will reflect the most recent change.

9. Contact

Questions about privacy: support@helaia.com.

Support

Get in touch

support@helaia.com

Helaia is a one-person operation. I read every email, but replies may take a few days. I’d rather give you a thoughtful answer than a corporate one — thanks for your patience.

QuickestLook is distributed under Apple’s standard End User License Agreement, available at apple.com/legal/internet-services/itunes/dev/stdeula.