JSON Tools, Validators, Converters & Troubleshooting

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Core tools

11 resources

tool

JSON Diff Online – Compare JSON Files

Compare two JSON files locally and inspect added, removed, and changed values by JSON path without uploading data.

tool

JSON Formatter Online – Format & Beautify JSON

Format and beautify JSON locally with 2-space, 4-space, or tab indentation, optional key sorting, syntax checks, and no uploads.

tool

JSON to CSV Converter Online

Convert nested JSON arrays or objects to spreadsheet-safe CSV, flatten fields into columns, and download the result without uploading data.

analyzer

JSON File Viewer Online – Open JSON Files

Open and view JSON files locally, validate syntax, format contents, and inspect errors without uploading files.

formatter

JSON Minifier Online – Compress JSON

Minify JSON locally, remove whitespace and line breaks, validate syntax, and copy compact API payloads without uploading data.

tool

JSON Repair Online – Fix Invalid JSON

Repair malformed JSON locally, review every automatic or suggested change, and compare the fixed output without uploading data.

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generator

JSON Schema Generator Online – Generate Schema from JSON

Generate JSON Schema from one or multiple JSON samples locally, merge optional fields and value types, infer standard string formats, and control contract strictness.

formatter

JSON Sort Keys Online – Alphabetize JSON

Sort JSON object keys alphabetically at every level, preserve array order and values, and process payloads locally without uploading data.

generator

JSON to Go Struct Converter Online

Convert JSON to Go structs locally with exported field names, JSON tags, nested types, array inference, and no sample-data uploads.

generator

JSON to TypeScript Online – Generate Interfaces from JSON

Convert JSON to TypeScript interfaces locally, generate nested object and array types, and copy reviewable code without uploading sample data.

analyzer

JSON Tree Viewer Online – Explore JSON Data

View nested JSON as an interactive tree, expand objects and arrays, search keys and string values, and inspect data locally without uploads.

Validate and diagnose

Checkers

3 resources

checker

JSON Error Checker Online – Find Syntax Errors

Find JSON syntax errors with line, column, absolute character, and nearby context. Check malformed payloads locally without uploading data.

checker

JSON Schema Validator Online – Validate JSON Data

Validate JSON data against a supported JSON Schema subset locally, review JSON Pointer errors, and keep payloads in your browser.

checker

JSON Validator Online – Check JSON Syntax

Validate JSON syntax locally, find errors with line and column details, and check API payloads without uploading data.

Transform data

Converters

1 resources

converter

JSON Unescape Online – Decode Escaped JSON

Unescape JSON strings and escaped text locally, decode backslash sequences, and format nested JSON without uploading data.

Troubleshoot

Problems and fixes

36 resources

problem

Bad Control Character in JSON – Find Invalid String Characters

Find bad control characters in JSON strings, including literal tabs and line breaks. Diagnose the exact source location and valid escape locally.

problem

Bad Unicode Escape in JSON – Fix \uXXXX Errors

Find malformed JSON Unicode escapes with missing digits or non-hex characters. Diagnose bad \uXXXX sequences locally with a corrected example.

problem

Comments in JSON – Remove Invalid JSON Comments

Remove // line comments and /* block comments */ from JSON while preserving comment-like text inside strings. Repair locally and review the cleaned result.

problem

Double-Encoded JSON – Detect and Decode JSON Stringified Twice

Recognize double-encoded JSON that parses to a string instead of an object. Remove one extra JSON encoding layer safely in your browser.

problem

Escaped JSON String – Decode Backslash-Escaped JSON Safely

Decode escaped JSON strings such as {\"name\":\"Ada\"}. Identify whether the value is JSON text, a JSON string, or plain escaped text before removing escapes.

problem

Expected Colon After Property Name in JSON – Find the Error

Find JSON errors where a quoted property name is missing its colon. Diagnose malformed key-value separators locally with line, column, and source context.

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problem

Expected Comma or Closing Brace in JSON – Fix Object Syntax

Find expected comma or closing brace JSON errors. Diagnose missing property separators, malformed values, and object boundaries with local parser context.

problem

Expected Property Name in JSON – Causes and Fixes

Diagnose expected property name JSON errors caused by unquoted keys, trailing separators, or malformed object members. Find the parser location locally.

problem

HTML Response Instead of JSON – Diagnose API Parse Errors

Find why an API returned HTML instead of JSON. Check status codes, redirects, login pages, proxy errors, Content-Type, and the raw response body locally.

problem

Infinity in JSON – Handle Infinity and -Infinity Safely

Find Infinity or -Infinity in invalid JSON. Replace non-finite values with a reviewable placeholder and choose the correct portable representation.

problem

Invalid Escape in JSON – Find Bad Backslashes

Find invalid JSON escape sequences and bad backslashes in strings. Diagnose Windows paths, unsupported escapes, and malformed Unicode escapes locally with source context.

problem

JavaScript Object vs JSON – Syntax Differences and Fixes

Compare JavaScript object literals with strict JSON. Find unquoted keys, single quotes, comments, undefined, NaN, functions, and other syntax JSON does not allow.

problem

JSON Trailing Comma – Find and Fix It Online

Find and remove trailing commas from invalid JSON. Repair commas before closing braces or brackets locally and review the exact change before using the result.

problem

JSON with UTF-8 BOM – Find and Handle the Invisible BOM

Detect a UTF-8 byte order mark at the start of JSON. Understand why some JSON.parse calls reject BOM-prefixed text and validate the document locally.

problem

JSON.parse Empty String – Why It Fails and What to Do

Find why JSON.parse fails on an empty string. Check empty HTTP bodies, storage values, and application state before parsing JSON locally.

problem

JSON.parse(undefined) – Why It Fails and How to Fix It

Find why JSON.parse(undefined) fails. Trace missing values, storage reads, API state, and already-parsed data before calling JSON.parse.

problem

Leading Zero in JSON Number – Why 01 Is Invalid

Find JSON number errors caused by leading zeros such as 01 or 007. Understand when values should be numbers versus quoted identifiers and validate locally.

problem

Missing Closing Brace in JSON – Find and Fix }

Find a missing closing brace in JSON objects. Repair a bounded object delimiter locally, review the inferred structural change, and validate the completed JSON.

problem

Missing Closing Bracket in JSON – Find and Fix ]

Find a missing closing bracket in JSON arrays. Repair a bounded array delimiter locally, review the inferred structural change, and validate the completed JSON.

problem

Missing Colon in JSON – Locate the Syntax Error

Find missing colons between JSON object keys and values. Inspect the parser location and nearby source locally, then correct the property separator without uploading data.

problem

Missing Comma in JSON – Find and Fix It

Find missing commas between JSON properties or array values. Repair bounded separator mistakes locally and review the inferred comma before using the result.

problem

Multiple JSON Objects – Fix Concatenated JSON or Use JSONL

Find why multiple top-level JSON objects fail as one JSON document. Wrap values in an array, split documents, or process newline-delimited JSON as JSONL.

problem

NaN in JSON – Why It Is Invalid and How to Handle It

Find and replace JavaScript NaN values in JSON. Review a null placeholder, choose the correct business representation, and keep the repair browser-local.

problem

Single Quotes in JSON – Convert to Valid JSON

Fix single quotes in JSON by converting JavaScript-style quoted keys and string values to valid double-quoted JSON, locally with a reviewable repair log.

problem

Truncated JSON – Detect and Fix Cut-Off JSON Data

Diagnose truncated JSON from incomplete downloads, logs, files, or copied API responses. Find where the document ends and verify the producer before patching data.

problem

undefined in JSON – Why It Is Invalid and How to Replace It

Find JavaScript undefined values inside JSON. Replace them with a reviewable null placeholder, then choose the representation required by your data contract.

problem

Unescaped Newline in JSON – Escape Line Breaks Correctly

Find literal newlines inside JSON strings and convert them to valid escaped line breaks. Diagnose multiline text locally without uploading data.

problem

Unescaped Quotes in JSON – Escape Double Quotes Correctly

Find unescaped double quotes inside JSON string values. Diagnose early string termination and correct embedded quotation marks locally.

problem

Unexpected End of JSON Input – Causes and Fixes

Find why JSON.parse reports Unexpected end of JSON input. Check truncated JSON, missing braces or brackets, incomplete strings, and empty responses locally.

problem

Unexpected Non-Whitespace Character After JSON – Fix Extra Data

Find extra characters or multiple top-level values after valid JSON. Diagnose concatenated objects, JSONL data, logs, and accidental suffix text locally.

problem

Unexpected Token < in JSON – Why It Happens

Find why JSON parsing fails on Unexpected token <. Check for HTML error pages, login redirects, 404 responses, and wrong API endpoints before changing JSON syntax.

problem

Unexpected Token in JSON – Find the Error

Diagnose Unexpected token in JSON errors with line, column, and nearby context. Find missing commas, invalid quotes, extra characters, and malformed values locally.

problem

Unexpected Token o in JSON – Causes and Fixes

Find why JSON.parse reports Unexpected token o. Diagnose already-parsed objects, [object Object] strings, and double parsing locally in your browser.

problem

Unexpected Token u in JSON – Why JSON.parse Fails

Diagnose Unexpected token u in JSON errors caused by undefined, missing storage values, empty application state, or parsing values before they exist.

problem

Unquoted JSON Keys – Add Required Quotes

Fix unquoted JSON object keys by adding required double quotes around identifier-like property names. Repair JavaScript-style objects locally and review inferred keys.

problem

Unterminated String in JSON – Find the Missing Quote

Find unterminated JSON strings caused by missing closing quotes, truncated text, or bad escaping. Inspect the parser location and corrected example locally.

Learn the workflow

Guides

2 resources

guide

How to Fix Invalid JSON Errors

Learn how to find and fix missing commas, unquoted keys, trailing commas, invalid escapes, hidden characters, and other common JSON errors.

guide

JSON Escaping Guide – Quotes, Backslashes & Unicode

Learn how JSON escaping works for quotes, backslashes, control characters, newlines, Unicode escapes, and double-encoded JSON with practical examples.