Free Online JSON5 Validator
A JSON5 validator checks whether a config file is valid JSON5 and reports the exact line if anything fails to parse.
In most cases, you know the config has JSON5 features but you need to check if they will survive the strict JSON step in the deploy pipeline. Our JSON5 Validator points at the exact line the parser stops on and names the JSON5 feature involved.
Using the JSON5 Validator, Step by Step
- Paste the JSON5 file: drop it into the editor on the left, drag a .json5 or .json file onto the input area, or click Upload File.
- Pick the check you need: JSON5 Validator for a pass-or-fail with stats, JSON5 Linter when you want every JSON5 feature flagged, JSON5 to JSON Check when a strict-JSON deploy step is next, or Structure Analyzer when the question is how deep the file nests.
- Read the report: a valid file lands a green stats panel with root type and key count, and a broken file lands a red panel with the exact parse-error line.
- Take the fix back to the editor: Copy puts the cleaned JSON5 on your clipboard, and the transformations list shows every change before you commit it.
What You Can Do with AIFreeForever's JSON5 Validator
Parse Error Locator
Names a parse failure by line and column.
Feature Linter
Flags every comment, trailing comma, NaN, and hex literal in the file.
Lossy Conversion Warning
Catches an Infinity or NaN before strict JSON quietly turns it into null.
Structure Depth Report
Comment Stripper
Removes // and /* */ lines in one pass.
Key Inspector List
Lists every key in the file with its type and nesting level.
Why Choose AIFreeForever's JSON5 Validator
| Capability | AIFreeForever | Typical Online Tools |
|---|---|---|
| Error Location | Line and column with the JSON5 feature named | Single red message, no location |
| Feature Detection | Comments, trailing commas, NaN, hex, decimals flagged | Pass or fail only |
| Lossy Conversion | Warns before Infinity or NaN becomes null | Silent data loss |
| Structure Analysis | Depth, node counts, JSON5-vs-JSON size delta | Not available |
| Privacy | Validation runs in your browser, nothing leaves the tab | Config uploaded to a server |
Built for Release Engineers, Tooling Authors, and Code Reviewers
When you ship a config to staging and it fails on a JSON5 feature the local linter did not catch, you need the exact line and the exact feature name. Our JSON5 Validator gives you that in one paste so the fix goes into the next commit instead of a full revert.
Most reliable way to catch a broken JSON5 config before deploy
Our JSON5 Validator uses the official JSON5 grammar, so a value like NaN or a trailing comma the linter would silently drop in strict JSON is named on the line it lives on before the file goes anywhere near a deploy pipeline.
Exact Line on Failure
The parse error names the line the JSON5 parser stopped on instead of a single red message.
Lossy Value Warning
Infinity and NaN values are flagged before the JSON conversion turns them into null.
Local Validation
The JSON5 parser runs in your tab so a private config never leaves the machine.
