Tool Guide
JSON Formatter & Viewer
A calm, browser-side JSON helper for formatting, inspecting, and navigating JSON payloads — ideal for debugging APIs, logs, and config files without copying data into external services.
What this tool does
The JSON Formatter & Viewer focuses on three things:
- Fast, readable formatting for any JSON payload.
- A collapsible tree viewer for exploring nested structures.
- Helpful error messages when your JSON is invalid.
Everything runs in your browser — nothing is uploaded or logged — so you can safely paste production payloads and internal data.
When to use it
- Inspecting an API response copied from browser devtools.
- Cleaning up minified JSON into something readable.
- Spotting missing commas, mismatched brackets, or stray characters.
- Understanding an unfamiliar payload by exploring it as a tree instead of raw text.
How it works internally
Parsing & validation
The tool trims the input first. Empty or whitespace-only input is treated as “no data” rather than an error. Real JSON is parsed using JSON.parse wrapped in a diagnostic layer that produces more helpful error messages and approximate line/column information.
Formatter
Successful parses are re-serialized with consistent indentation (typically 2 spaces). This makes payloads easy to scan and compare, regardless of how the backend originally formatted them.
Tree viewer
In tree mode, objects and arrays are rendered as nested nodes with expand/collapse controls. Large branches are collapsed by default so you can focus only on the parts you care about.
Common usage patterns
Format-only workflow
- Paste raw or minified JSON into the input pane.
- Let the tool auto-format it.
- Copy the prettified output back into your editor or commit.
Explore & debug workflow
- Paste an unknown payload from an API response.
- Switch to tree view to see the overall shape.
- Expand nested objects and arrays until you find the field you need.
Troubleshooting
| Issue | Likely cause | What to try |
|---|---|---|
| Parse error on valid-looking JSON | Hidden characters, trailing commas, or comments. | Check the highlighted position and remove comments, dangling commas, or stray characters. |
| Tool feels slow on huge payloads | Rendering a very large tree in the browser. | Use text formatting only, or trim unnecessary fields before pasting. |
| Numbers or dates show up as strings | They were serialized as strings by the backend. | This is normal JSON behavior; update the backend if you need typed values instead. |
Roadmap
- Optional JSON5 mode (comments, trailing commas).
- Schema-aware validation and inline hints.
- Side-by-side JSON diff and merge.
- Streaming view for extremely large payloads.