JSON Viewer

Fast offline JSON & JSONL viewer for developers. Handles 100MB files.

JSON Viewer is a fast, offline JSON and JSONL viewer for Android, built for
developers who actually have to look at API responses, log dumps, and config files on their phone.

We built it because every other JSON tool we tried either choked on real-world payloads or buried the data behind sign-up walls. This one just opens the file.

Built for large files:
• Smoothly handles JSON documents up to 100MB and trees with 10,000+ nodes
• Virtualized rendering keeps scrolling fluid no matter how deep the structure
• Search runs against a pre-built index, so finding a key in a massive payload
is instant after the file loads

Real format support:
• .json — standard JSON files
• .jsonl / .ndjson — line-delimited JSON parsed as a single browsable array,
with per-line error reporting that tells you exactly which line is broken
instead of failing the whole file

Designed for inspection, not just viewing:
• Tap any primitive to open a detail sheet showing its type, length, byte size,
and full JSONPath
• Copy the value, or copy the path, with a single tap
• Expand and collapse individual nodes, or use Expand All / Collapse All to
navigate huge structures quickly
• Type-aware colors and icons distinguish strings, numbers, booleans, nulls,
objects, and arrays at a glance

Search that actually helps:
• Search across keys and values, case-insensitive
• Matching nodes are highlighted in place and the tree auto-expands their
parents so you can see results in context
• A live counter shows how many matches your query produced

Built for the way developers work:
• Recent files list keeps your last 10 documents one tap away, with sizes and
timestamps
• Light and dark themes follow your system setting
• Haptic feedback on the interactions that matter
• Full screen-reader and accessibility support

Local and private:
• Everything happens on your device. No accounts, no upload, no cloud
• The app works fully offline

If you live in JSON — debugging an API response on the train, sanity-checking
a config before you push, or opening a log file your backend dropped in cloud
storage — this is the viewer we wished existed.

Note: JSON Viewer features a banner ad to support the app development.