Single quotes
JSON: String values and keys must use double quotes.
JSON5: Single quotes are allowed in many cases.
JSON and JSON5 Differences
Quickly understand why JSON5 syntax can look valid but still fail strict JSON validation, then jump back to the JSON tool to check your payload.
Core differences between JSON and JSON5
Comments
JSON: Comments are not part of the standard.
JSON5: Inline and block comments are supported.
Trailing commas
JSON: A trailing comma makes the payload invalid.
JSON5: Trailing commas are allowed.
Quoted keys
JSON: Object keys must be wrapped in double quotes.
JSON5: Unquoted identifier-like keys are allowed.
Why these differences cause validation errors
Many tools, APIs, and backends use strict JSON parsing, not JSON5 parsing.
- When a parser follows strict JSON rules, JSON5-only syntax is rejected immediately.
- JavaScript-like convenience syntax can look normal in code, but still be invalid as data exchange JSON.
- Fix the first reported error position first; later errors are often side effects.
When you should use standard JSON
- API request and response payloads that need predictable parsing across services.
- Data exchange between systems, teams, and languages where strict interoperability matters.
- Configuration files consumed by tools that expect strict JSON only.
FAQ: JSON vs JSON5
Is JSON5 a replacement for JSON?
No. JSON5 is a more flexible format, but many systems still require strict standard JSON.
Why does my config work locally but fail in an API?
Local tooling may accept JSON5 syntax, while the API parser often accepts strict JSON only.
How can I convert JSON5-style content to standard JSON?
Remove comments, use double quotes, remove trailing commas, and quote all keys.
Where can I check if my content is strict JSON?
Use the main Toolbye JSON tool to validate and format the payload with strict parsing.
Related pages
JSON Formatter & Validator
Return to the main tool to validate strict JSON content now.
How to Fix JSON Validation Errors
Need practical fixes after comparison? Use this page next.
JSON Format Error Online Checker
Need a quick check flow? Use this scenario page to validate JSON online.