Smartcat is a free JSON translator online: drop in a .json file and get it back in any of 280+ languages, with string values translated, keys and nesting untouched, and placeholder tokens locked as tags.
More than 80 of the world’s largest companies have chosen Smartcat
Yes. You can translate a JSON file online free with Smartcat for 15 days: 15,000 Smartwords, no credit card, and full access to translation capabilities, including the API. It is a free trial account, not a free plan or an anonymous tool, so you create an account before your first upload. When the 15 days end, translation stops until you choose a paid plan, and nothing is charged.
A free JSON translator, or JSON file translator, translates the string values in a .json file and leaves the structure alone: keys, nesting and placeholder tokens such as {name}. Smartcat parses the file instead of treating it as plain text, so you upload your file, pick languages and download valid JSON in each language, with every key where it was.
15
day free trial
When the trial ends, translation stops until you pick a plan. The files you already downloaded are yours to keep.
15K
Smartwords included
The trial includes 15,000 Smartwords. Translating one source word into one target language uses one Smartword, so a 5,000-word file in three languages uses 15,000.
280+
target languages
Pick one source language and as many targets as you need in one project, and download one JSON file per language.
{
"checkout": {
"title": "Your cart",
"items": "{n, plural, one {# item} other {# items}}",
"greeting": "Hi {name}, ready to pay?"
}
}{
"checkout": {
"title": "Ihr Warenkorb",
"items": "{n, plural, one {# Artikel} other {# Artikel}}",
"greeting": "Hallo {name}, bereit zum Bezahlen?"
}
}An online JSON translator that treats the .json file as plain text translates whatever it can see, including the keys and placeholders your code depends on, so the file stops parsing. Smartcat reads the JSON structure first and translates only the string values.
“title” becomes “título”, and your app can no longer find the string.
Smartcat imports string values as text to translate. Keys and nesting are never offered for translation.
Tokens such as {count} or %s come back translated, moved or missing.
Tokens are imported as non-editable tags, matched by regular expressions you set once.
A stray quote or a lost bracket, and the build fails on the translated file.
Keys and nesting come back where they were, in one valid JSON file per target language.
You paste the whole file again for each language and every change.
Translation memory keeps approved strings, so an update covers only new and changed text.
The free trial is the full JSON translator, not a cut-down tier: the editor, translation memory, glossaries, multi-file upload and the API are all included. A paid plan adds time, a Smartwords allowance shared by unlimited users and, on enterprise plans, SSO and role-based access.
| Free trial | Paid plan | |
|---|---|---|
| How long | 15 days, then translation stops until you subscribe | For as long as you subscribe |
| Smartwords | 15,000 | A Smartwords allowance shared by unlimited users |
| JSON file translation | Full: 280+ languages, multi-file upload, the translation editor | The same |
| Translation memory and glossaries | Included | Included, and only new and changed strings are billed when you re-translate |
| API | Included: generate a key in Settings > API | Included on plans with API access |
| Security | SOC 2 Type II, encryption in transit and at rest | The same, plus SSO and role-based access on enterprise plans |
| Best for | One file or one batch, and the job ends there | Re-translating on every release, with several people on the locale files |
Prices for every plan are on the Smartcat pricing page, no call required.
To translate JSON online for free, upload the .json file to Smartcat, pick your target languages, let AI translate the string values, check short strings in the editor and download one file per language. For flat, nested and i18next files, follow the step-by-step guide to translating a JSON file.
Drag your .json file into the uploader at the top of this page, or sign up and create a project. The trial starts when you sign up.
Choose one source language and one or many targets from 280+. Each target language gets its own output file.
String values are translated with your glossary and translation memory. Keys, nesting and placeholder tags stay where they were.
Open the JSON translation editor to read source and target strings side by side. Short UI strings are the ones worth a human glance before you ship.
Same keys, same nesting, new language: one output JSON file per target language.
Beyond one-off files, you can translate the JSON behind app UI strings, API documentation, website content and in-game text with Smartcat’s free JSON translator. The same upload scales to the locale files your product ships every sprint.
Smartcat translates any JSON file the same way: string values are translated, and keys, nesting and placeholders are not. That holds for i18n locale files, nested objects, plurals, large files and batches, which are the cases people ask about most.
Locale files come in a few shapes. Smartcat handles each one without flattening or renaming anything.
Locale files such as en.json for i18next or React Native are key-value JSON. Smartcat translates the values and returns de.json, fr.json and the rest with identical keys.
Nested objects keep their shape: Smartcat translates the strings at every level and writes the tree back as it was. For the element-by-element breakdown, including the plural caveats, see what survives translation on the JSON translator page.
The same paths in every language
Plurals can be kept as ICU MessageFormat or edited as native plural segments in the editor. On export, Smartcat writes plurals back as ICU-compatible strings.
Placeholder tokens are imported as non-editable tags. Smartcat matches them with regular expressions you set once on the Placeholders tab in Settings, so the pattern your codebase uses is the pattern that gets protected.
Patterns you can lock as tags
Free doesn’t mean one small file at a time.
Smartcat accepts document and project files up to 6 GB. Split a JSON file over 1 GB into smaller parts so it processes faster.
Upload a batch of JSON files into one project, pick every target language once, and download one output file per language.
To translate a JSON file to English, set the file’s language as the source and English as the target, and Smartcat returns en.json with the same keys. It supports 280+ languages, including right-to-left ones.
When the same file changes every sprint, translation memory reuses approved strings, so only new and changed strings are billed. Teams connect repositories through the API, the CLI or the Git integration as part of software localization with Smartcat.
Each coworker handles one step of JSON translation, from the first draft to the final check. You or your reviewers approve every language before download.
Chief of Staff
Tell your Chief of Staff which JSON files and languages you need, and it coordinates the coworkers that translate and check them.
Content Translator Coworker
Translates the string values in your JSON files into 280+ languages with your glossary and translation memory, with keys and placeholders locked.
Content Update Coworker
Helps find the strings a source change affects and re-translates only the new or changed ones, so every locale file stays current.
Reviewer Coworker
Pre-reviews every language for fluency, tone and terminology, so your reviewers approve a strong draft of each locale file.
Quality Assurance Coworker
Checks each translated file for terminology, formatting and tag errors and gives it a quality score before export.
Move strings from your repository or design tool into translation and back, or translate content where your teams already work. See all integrations
GitHub, GitLab, Bitbucket
Sync JSON locale files from your repository and get translations back as files.
Smartcat CLI
Import and export JSON keys from the command line or any CI/CD script.
REST API
Upload JSON files and pull translated ones from your own tooling.
Android
Translate Android string resources kept in your Git repository.
Figma
Translate design text with keys and variants, and export it as JSON.
Contentful
Translate structured entries in your headless CMS.
Zendesk
Translate the help-center articles your users read.
Google Drive
Translate specs, release notes and docs kept in Drive.
WordPress
Publish your marketing site in the same languages as your app.
Sitecore
Keep web content aligned with your product locales.
Kaseya cut localization costs by 70% with Smartcat and made UI localization part of each development cycle through its GitHub integration. Each number below comes from the Kaseya case study.
70%
lower localization costs
Kaseya cut localization costs by 70% and reinvested the savings in 8+ additional languages.
10+
languages synced from GitHub
Kaseya’s GitHub integration made UI localization part of each development cycle, with translated strings pushed back to the repository, across 10+ languages.
“We’re coding with AI, so we’re releasing product updates every day, a couple times a day. There’s no way to keep up with that. This rate of change is one of the reasons why Smartcat is so necessary.”
Before the first upload, people ask whether keys get translated, what happens on day 16, whether files train AI and whether the API works on the trial. Smartcat’s answers are below, including the one thing a free JSON translator won’t do for you.
No. Smartcat imports only string values as text to translate. Keys and nesting are never offered for translation, so they can’t change.
Never translated
Translation stops until you choose a paid plan. Nothing is charged automatically, and the files you already downloaded are yours to keep.
No. Your content is never used to train public AI models, and trial accounts run on the same SOC 2 Type II compliant infrastructure as paid plans.
Yes. Trial accounts can generate an API key and import and export files through the REST API or the CLI, so you can test the flow you would run in CI/CD.
No. Upload the file in your browser and download the result. Developers who want automation can add the API or the CLI later.
Not always, and that’s the honest limit. One-word strings such as “Save” or “Close” carry no context, so machine translation can’t tell a button from a discount.
Read one-to-three-word strings in the editor before you ship.
JSON translation on Smartcat’s free trial is protected exactly as on paid plans: SOC 2 Type II compliance, encryption in transit and at rest, isolated workspaces, and no training of public AI models on your strings. See the details on the Smartcat security page.
SOC 2 Type II and ISO 27001
Smartcat is SOC 2 Type II compliant, ISO 27001 certified and isolates every workspace, on the trial and on paid plans.
Encryption in transit and at rest
Your JSON files are encrypted while they upload, while they are stored and while they download.
Never used to train public AI models
Strings you translate are never used to train public AI models.
Role-based access controls
Set who can view, translate, review and approve files by team or role on enterprise plans.
Single sign-on (SSO)
Sign in through your existing identity provider on enterprise plans.
Deletion on request
Content is deleted or returned within 30 days of a written request.
Smartcat’s JSON guides cover what comes after a free translation: how to translate JSON files step by step, JSON localization for product teams, and locale files for English and every other language.
A free JSON translator such as Smartcat translates the text values in a .json file and leaves the structure alone. Keys, nesting and placeholder tokens like {name} come back as they were, so the translated file still loads in your app. A plain text translator can’t tell keys from values, which is why pasted JSON often comes back broken.
The best free JSON translation tool returns valid JSON you can ship. Many “json translate” tools treat the file as plain text, so whichever JSON language translator you test, check that it never translates keys, locks placeholders and keeps nesting and plurals intact. Smartcat fits when you want an editor, translation memory and many languages at once; for one string translated once without an account, a paste tool is quicker.
Sign up for Smartcat’s free trial, drop the .json file into a project, pick your target languages and let AI translate the string values while keys and placeholders stay locked. Check short UI strings in the editor, then download one JSON file per language. The step-by-step guide to translating a JSON file covers flat, nested and i18next files.
Yes, for 15 days. Smartcat’s free trial includes 15,000 Smartwords and full access to translation capabilities, including the API, and it needs no credit card. There is no free plan: when the trial ends, translation stops until you choose a paid plan, and you enter payment details only if you subscribe.
No. Smartcat asks you to create a free trial account before it translates a file, because the JSON is parsed into a project where keys are locked and approved translations are kept. Tools that translate pasted text without an account usually treat JSON as plain text, so check their output for translated keys.
Only for a few strings, not for a whole file. Smartcat parses the JSON, while general-purpose translators and chat tools treat it as text: they may translate keys, rewrite placeholders or drop a quote, and the file stops being valid JSON. You also get no translation memory, so every update starts from zero.
As many as 15,000 Smartwords cover. On Smartcat’s free trial you upload a batch of JSON files into one project and translate them into every target language you pick. One source word into one target language uses one Smartword, so 3,000 words across five files into five languages uses all 15,000 Smartwords.
Keys, nesting and placeholder tags come back as they were. Smartcat translates only the string values, locks tokens such as {name} or %s so translators can’t edit them, and writes plurals back as ICU-compatible strings. Each target language gets its own valid .json file. For the element-by-element breakdown, see the JSON localization page.
Up to 6 GB. Smartcat accepts document and project files of up to 6 GB each, according to its help center article on file upload limits, and files over 1 GB process faster when you split them into smaller parts. Most locale files are a few kilobytes to a few megabytes, so size rarely limits a JSON translation.
Yes. Smartcat exports JSON either flat or structured. In a software localization project, nested keys are written back as a structured tree using a path separator, so a key such as checkout.title returns inside the checkout object of de.json, exactly as it sat in en.json. Flat files stay flat, and the same export options apply to YAML.
Yes. Smartcat’s free trial includes glossaries and translation memory. Add product names and UI terms to a glossary, and AI translation applies them to every string in your JSON files; translations you approve go into translation memory, so the next upload of the same file reuses them instead of translating them again.
Stay on Smartcat’s free trial if you have one file or one batch and the job ends there. A paid plan pays off when you re-translate on every release, because only new and changed strings are billed, when several people touch the locale files, or when you want terminology enforced across products. Prices are on the Smartcat pricing page, no call needed.
Yes. Smartcat translates YAML, Android strings.xml and iOS .strings files alongside JSON, through the web interface, the REST API or the CLI, with the same locked keys and placeholders. Apple .stringsdict and .xcstrings files work as file uploads. For Android resources and other XML, see the XML translator.
Didn’t find your answer? Talk to a localization specialist
Trademark notice. Google Translate is a trademark of Google LLC, and ChatGPT is a trademark of OpenAI. Smartcat is not affiliated with, endorsed by or sponsored by either company. All product names on this page are used only for identification.
Upload your JSON and download it in a new language with its keys and nesting where you left them. Translating on every release? Book a demo and see the team workflow.