JSON Lint Online
Lint JSON online. Catch missing commas, bad quotes and broken brackets, then clean the file with one-click formatting. Free JSONLint alternative.
Part of the free JSON Formatter & Validator. Runs in your browser — nothing is uploaded.
JSON Lint Online
Linting JSON means finding structural mistakes before they reach a parser: a missing comma between properties, an unclosed bracket, a stray character. Paste your text and the checker reports what and where, so you fix one issue at a time.
Worked example: A missing comma between properties
JSON with a typo
{
"id": 1
"name": "Ada"
}Lint result
✗ Invalid JSON Expected ',' or '}' after property value in JSON at position 14 (line 3 column 3)
Practical tip
Fix errors from the top down. One early mistake, such as a missing comma, can make the parser report later lines as invalid too.
How to use this JSON Formatter
- 1Use the live tool above — it runs entirely in your browser and never uploads your data.
- 2Paste the sample from the worked example, or use your own input.
- 3Copy the result, then adapt the same steps in your editor, script, or pipeline.
JSON Lint Online FAQs
What is the difference between JSON lint and a JSON formatter?
Lint checks whether the JSON is valid. A formatter changes whitespace to make valid JSON readable. This page offers both in one place.
Does lint check for duplicate keys?
Standard parsers accept duplicate keys and keep the last one, so many validators stay silent. Review repeated keys manually when data looks wrong.
More JSON Formatter pages
- Format JSON OnlineFormat JSON online in one click. Paste messy or minified JSON and get clean, indented, readable output instantly. Free, private, runs in your browser.
- JSON Validator OnlineValidate JSON online and find syntax errors fast. Paste your JSON to check whether it is well-formed and see the exact position of any error.
- Minify JSON OnlineMinify JSON online by stripping whitespace and line breaks. Shrink payloads for APIs, configs and bundles without changing the data. Free and private.
- Fix Trailing Comma Errors in JSONGetting "Unexpected token }" or "Expected double-quoted property name"? Paste your JSON to locate the trailing comma and fix it in seconds.
- Fix JSON Single Quotes ErrorsJSON requires double quotes. See why single-quoted keys and strings fail, check your text with the validator, and fix the quotes quickly.
- Format API Response JSONPretty print an API response from curl, Postman or fetch. Paste the raw JSON body and read nested results, arrays and nulls clearly.
- JSON Viewer OnlineView JSON as a collapsible tree. Explore nested objects and arrays, expand only what you need, and copy values from any level. Free and browser-based.
- Format package.json OnlineFormat package.json with consistent 2-space indentation. Paste your manifest to tidy scripts and dependencies before committing. Free, runs locally.
- JSON Pretty Print With Tabs or SpacesPretty print JSON with 2 spaces, 4 spaces or tabs to match your style guide. Paste JSON, pick the indent and copy the result. Free and private.