Drop in a .json file and get back JSON in any of 280+ languages: string values translated, keys and nesting untouched, and your placeholder tokens locked as tags.
Trusted by leading global teams for all their localization needs
Yes — you can translate a JSON file online free with Smartcat. Free means 15 days with 15,000 Smartwords and no credit card, with full access to translation capabilities (the API is paid-only). Upload your file, pick languages, and download JSON with every key where it was.
15 days
free, no credit card
Smartcat does not have a free-forever plan; it has a free 15-day trial with no credit card required. You enter payment details only if you subscribe afterwards.
15,000
Smartwords included
Translation is metered in Smartwords, at one Smartword per source word. The trial allowance covers a single file or a batch comfortably.
280+
target languages
Pick one source and as many targets as you need in one project, and download one output file per language.
What the free trial covers
JSON file translation into 280+ languages, multi-file upload, the translation editor, translation memory and glossaries, and a trial allowance of 15,000 Smartwords — full access to translation capabilities for 15 days, with no credit card.
How translation is metered
Translation is metered in Smartwords, at one Smartword per source word. When the trial ends, translation stops until you pick a paid plan. There is no free-forever plan.
What the trial does not include
The API. API access is a paid feature of the Anticipate and Autonomous plans, it requires a company account rather than a freelancer one, and it is not switched on for trial accounts.
Keys are never translated
Only the string values change. Keys, numbers, booleans and nesting come back exactly as they went in.
Nested objects keep their shape
Nested object structures are preserved, and plurals can be kept as ICU MessageFormat. For the element-by-element breakdown, including the plural caveats, see what survives translation on the JSON translator page.
Placeholders are locked as tags
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.
1
Upload the file
Drag your .json into the box above. No account gymnastics: the trial starts when you sign up, and no card is required.
2
Pick your languages
One source, one or many targets, from 280+.
3
Let the AI translate
String values are translated; keys, nesting and placeholder tags are left where they were.
4
Check anything you want to fix
Open the editor to read the strings side by side. Short UI strings are the ones worth a human glance before you ship.
5
Download the translated file
Same keys, same nesting, new language — one output file per target language.
For development teams
Wire JSON localization into your CI/CD pipeline with the Smartcat API — a paid feature of the Anticipate and Autonomous plans that needs a company account, and one that is not switched on during the free trial. Stop spending development hours on manual file handling.
For product managers
Launch features globally from day one. Our platform enables simultaneous translation across all target languages, eliminating regional release delays.
For L&D and marketing teams
Manage multilingual content at scale. Create and maintain training or marketing that stays in sync with product updates across all languages.
for ease of setup on G2
for ease of use on G2
enterprise brands
Type II compliant
Free for 15 days with 15,000 Smartwords, no credit card. There is no free-forever plan: after 15 days you pick a paid plan or stop.
50%
increase in productivity
expondo increased productivity by 50% while reducing outsourcing costs by 50%, localizing in-house across 18 countries.
1,000 hours
admin time saved yearly
The City of Seattle saved about 1,000 hours of yearly administrative and project-management time by automating paperwork and payment for the 50+ community reviewers it works with, and cut translation expenses by 17%.
31 hours
of work time saved monthly
Babbel's marketing and L&D teams save 31 hours of work every month. Time they can now use for more strategic tasks.
Same infrastructure as paid: Smartcat is SOC 2 Type II compliant, files are encrypted in transit and at rest, and workspaces are isolated. Trial accounts are not a lower security tier. Details on the security page.
Upload your JSON, download it back in a new language with its keys and nesting where you left them. No credit card, no surprise paywall mid-file.
For 15 days, yes — 15,000 Smartwords, no credit card, with full access to translation capabilities (the API is not included). There is no free-forever plan; after the trial you choose a paid plan or stop.
No. You enter payment details only if you subscribe after the trial.
The documented ceiling is global rather than JSON-specific: 6 GB per document or project file, and the guidance is to split anything over 1 GB into smaller parts so it processes faster.
On file count there is no cap at all — batch uploads of hundreds of files are supported, and that does not change between the trial and any paid plan. Plans differ on integrations and Marketplace billing, not upload limits.
Yes — pick multiple target languages in one project and download one output file per language, all generated from the same source.
Keys are never translated. Placeholder tokens are locked 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. Nested objects keep their shape, and plurals can be kept as ICU MessageFormat. For the element-by-element breakdown, see the JSON translator page.
Two honest things.
What you get here for the same zero dollars is a real editor, structure safety, and a security posture you can show your team.
Stay on the free trial if you have one file, or one batch, and the job ends there — the trial is genuinely enough for that.
A paid plan starts paying for itself when:
Pricing is on the pricing page — no call required to see it.