Coverage per file
How much of the base key set each file carries.
Charts appear here once you run an analysis.
i18n JSON Validator BETA
Validate your localization files and catch missing keys, inconsistencies and potential issues before release.
Free to use
No registration
Privacy-first
Files are validated on our servers and never stored or shared.
Supported structure
- ✓Flat JSON
{ "key": "value" } - ✓Nested JSON
{ "key": { "nested": "value" } } - ✓Placeholders
{name}, %s, {{value}} - ✓HTML tags
<b>, <a>, <br> and more
Tip: Name your files with the language code (e.g. en.json, pl.json, de.json) for best results.
Files are validated on our servers. We do not store or share your data.
Visual analytics
Where the locale files diverge
Coverage per file, what kind of problem each one has, and where the two overlap.
Issue breakdown
Every finding across all files, by type.
Charts appear here once you run an analysis.
File and issue matrix
Which file carries which problem, and how much of it.
Charts appear here once you run an analysis.
Value consistency
Of the keys that do exist, what actually differs from the base.
Charts appear here once you run an analysis.
Use cases
When to validate locale files
Translation drift is silent: the app keeps rendering, just not what you wrote.
Before a release
Catch keys added in one language and never propagated, while the release is still yours to hold.
After a translation hand-off
Confirm that returned files kept every placeholder and every inline tag exactly as the base had them.
Merging two branches
Two people editing the same locale file usually produces duplicates and orphans. This names them.
Scope and limits
What this validator does, and what it will not do
It compares structure. It never rewrites, translates or judges the meaning of your copy.
A validator, not a translation service
Files are compared against a base file and reported on: missing and extra keys, type mismatches, placeholder and inline-tag differences, empty values and strings still identical to the base. No content is translated, suggested or stored, and the files are discarded as soon as the report is built. A string flagged as untranslated may be perfectly correct, as brand and technical terms often are.
Help
FAQ
The questions a validation report tends to raise.
How is the base file chosen?
By default the largest, most complete file in the set, since that is almost always the source language. Every other file is compared against it, so the base is 100% by definition.
What counts as a placeholder mismatch?
The tokens the runtime interpolates, such as {name} or %s, differ between the base string and the translation. That is a real defect: at best the value never appears, at worst the formatter throws.
Why is a key reported as untranslated?
Its value is byte-identical to the base. Often that is a brand name, a code sample or a unit, and it is correct. It is reported separately from hard errors for exactly that reason.
Are my files uploaded and kept?
They are sent to our server to be parsed and compared, then dropped. Nothing is written to disk, indexed or shared.
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