BigLeaf: Large JSON Viewer
Open huge JSONL & NDJSON logs
Only for Mac
Free · In‑App Purchases
Mac
Completely free. Open a 21.5GB JSONL with ~69MB of RAM. First records in ~0.2s at any size. Read-only, two-pane, instant search. Your files never leave your Mac.
Open a 5GB JSONL in seconds — without watching your editor eat 50GB of RAM.
BigLeaf is a read-only viewer for large JSON, JSONL, and NDJSON files. It opens the file with memory mapping and a sparse index instead of loading the whole thing into RAM, so the first records appear almost immediately and memory stays flat as the file grows.
Built for files that break other tools
- Opens a 21.5GB JSONL using about 69MB of RAM (measured on Apple Silicon).
- First records on screen in about 0.2 seconds, whether the file is 200MB or 20GB.
- Memory use does not scale with file size — there is no built-in size limit. Tested up to 100GB.
Skim, then inspect
- A two-pane window: scroll millions of records on the left, expand the selected record as a collapsible tree on the right.
- Smooth virtual scrolling over tens of millions of records.
- Jump straight to record number N.
Search like grep, with a UI
- Literal substring search across the whole file, with a progress bar you can cancel.
- Filter View shows only matching records; Jump Mode keeps the full list and steps between hits.
- Copy a value, a key path, the raw line, or the pretty-printed record straight into your tickets, jq, or chat.
Real-world data, not just clean exports
- Lines that are not valid JSON stay in the list as raw records instead of stopping the viewer.
- Root-array JSON (a single document whose top level is an array — typical of DB and API dumps) opens in the same two-pane view.
- Drag in a .log or .txt file: the format is detected from the content, not the extension.
Private by design
Your files never leave your Mac. BigLeaf opens files read-only and never holds a write handle to your data. There is no network code apart from StoreKit for optional tips — no accounts, no analytics, no telemetry, no cloud. App privacy is Data Not Collected.
Completely free
Every feature, any file size, no strings. No account, no subscription, no paywall — the 100MB limit from earlier versions is gone. If BigLeaf saves your day, there is an optional Tip Jar in the Help menu. Tips support development and unlock nothing.
Free. No subscription. Requires macOS 14.0 or later. Universal.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
BigLeaf is now completely free.
The 100MB file-size limit is gone. Every feature works on every file, at any size, for everyone — no account, no subscription, no paywall.
If BigLeaf saves your day, there is now an optional Tip Jar in the Help menu. Tips support development and unlock nothing.
If you bought the Pro unlock: your purchase funded exactly this work. Thank you for backing BigLeaf when that was the only way to support it. You lose nothing — you already had everything.
The developer, KEISUKE OIKAWA, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- KEISUKE OIKAWA
- Size
- 2.7 MB
- Category
- Developer Tools
- Compatibility
Requires macOS 14.0 or later.
- Mac
Requires macOS 14.0 or later.
- Mac
- Languages
- English and Japanese
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- Massive Tip $100.00
- Grand Tip $20.00
- Small Tip $5.00
- Generous Tip $10.00
- BigLeaf Pro $14.99
- Copyright
- © 2026 Keisuke Oikawa