Add your JSON file
Drop one or more .json files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
JSON to ARB
Restructuring .json data as .arb changes the serialization without touching the values themselves. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop JSON files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting JSON data to Application Resource Bundle
Restructuring .json data as .arb changes the serialization without touching the values themselves. A .json file holds JavaScript Object Notation: nested objects, arrays, strings, numbers, booleans, and null written in a strict text syntax. It is the default data language of the web — most APIs speak nothing else.
An .arb file is an Application Resource Bundle: a JSON object in which each key maps to a translatable string, and keys prefixed with @ carry that string's metadata — its description, its placeholder types and their formatting. It is the localisation format Flutter's intl tooling generates from and compiles to typed Dart accessors. For this route the practical draw is metadata lives with the string, so translators get context without a separate file and iCU MessageFormat covers plurals and gender without extra entries — balanced against the @-key convention doubles the entry count and looks odd to anyone new to it, which is worth knowing before you commit a large batch.
Why convert JSON to ARB?
The practical trigger for this conversion is usually a mismatch: with .json, no comments — a perpetual annoyance for configuration files. Switching to .arb buys you metadata lives with the string, so translators get context without a separate file, which is why it is the better fit for localising a Flutter application through gen_l10n. Because the conversion runs locally, trying it costs nothing but a few seconds of compute on your own machine.
JSON vs ARB at a glance
| Aspect | JSON data (.json) | Application Resource Bundle (.arb) |
|---|---|---|
| Format type | Text-based — characters and structure, so there is no visual quality loss | Text-based — characters and structure, so there is no visual quality loss |
| How it stores data | exactly six value types; no dates, no comments, no trailing commas — the strictness is deliberate | the document is a single JSON object; ordinary keys map to strings, and @-prefixed keys map to metadata objects for the key of the same name |
| Strongest at | rEST and HTTP API request and response payloads | localising a Flutter application through gen_l10n |
| Weak spot | no comments — a perpetual annoyance for configuration files | the @-key convention doubles the entry count and looks odd to anyone new to it |
Pick ARB as the output
Select .arb in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if ARB is selectable, the route is real and validated.
Convert on your device
Press Convert. The restructuring is plain local parsing — your data is never posted to a server for processing.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid ARB file. Outputs keep the original filename with the .arb extension.
JSON to ARB questions, answered
Will converting JSON to ARB lose quality?
There is no visual quality to lose — json is text-oriented and arb is text-oriented, so the question is structural fidelity. Text, ordering, and basic structure are preserved; complex layout, embedded objects, and styling beyond the target's model are simplified.
Is it private to convert JSON files here?
Yes — the .json file is processed inside your browser tab and never uploaded. The restructuring is plain local parsing — your data is never posted to a server for processing. Close the tab and the file is gone from memory.
Where will the ARB file work?
Flutter's tooling reads ARB natively and the major translation platforms support it; elsewhere it is just JSON. Novus Convert flattens the bundle locally, skipping @-prefixed metadata keys so they do not appear as translatable entries, and converts to and from the other localization formats. Placeholder metadata and ICU plural structure are not representable in flat targets.
Will the ARB file be bigger or smaller than my JSON?
It depends on the content: the document is a single JSON object; ordinary keys map to strings, and @-prefixed keys map to metadata objects for the key of the same name. Convert one representative file first and compare before batch-processing a large set.