Large JSON Viewer

Why regular JSON viewers choke on big files

Most browser-based JSON tools call JSON.parse on the whole file and render every node into the DOM at once. That works fine for a few megabytes; at hundreds of megabytes it blocks the main thread for seconds and can render a tab unresponsive. This viewer avoids both problems:

• • Streaming parse — the file is read and tokenized incrementally, without materializing the whole document in memory up front
• • Virtualized tree — only the rows currently visible in the viewport are rendered, so the DOM stays small even at 200k+ nodes
• • Lazy expansion — nested objects and arrays are parsed further only when you actually expand them
• • Search with a progress indicator, so scanning a huge file gives you feedback instead of freezing the UI
• • We never see your data — no upload, no backend; everything happens in your browser tab

Typical use cases

• • Inspecting a large API export or database dump saved as JSON
• • Reviewing a bulky configuration or infrastructure-as-code file
• • Auditing a large analytics or logging payload before piping it into another tool
• • Spot-checking a machine learning dataset or model output file

Line-delimited instead?

If your large file is actually one JSON object per line rather than a single document, the NDJSON Viewer paginates by line instead of building one giant tree, which is usually a better fit for logs and exports. For everyday, smaller JSON, the plain JSON Viewer has the same tree and JSONPath tools without the streaming overhead.

FAQ