File-level translation with translation memory and glossaries behind one API — on the Anticipate and Autonomous plans, company accounts only. There is no free tier and no self-serve switch, so access starts with a scoping call. The docs are public if you’d rather read first.
Trusted by developers and localization teams at 1,000+ enterprise brands
No
free API tier
Not permanently, and not as part of the free trial. There is no free-forever tier, no free API key and no unlimited free usage — if you find one advertised, it is not this API.
4 req/s
rate limit, every method
Applied to every Smartcat API method; exceeding it returns 429 TOO MANY REQUESTS. There is no per-plan differentiation — the limit is the same on Anticipate and Autonomous, and it is documented publicly in the rate limits section of the guides.
50+
file formats, no reduced API set
The API reaches the same formats the platform supports. The software-localization API additionally exports json, structured-json, yaml, structured-yaml, ios-strings and android-xml. Executables and scripts are blocked for security.
The platform trial: 15 days, no API
The 15-day platform trial is real, needs no credit card and includes 15,000 Smartwords, and it is a fine way to see how Smartcat translates your files in the UI. It just does not include API access, so it cannot tell you anything about the integration.
API access: paid plans, company accounts
API access ships with the Anticipate and Autonomous plans and requires a company account rather than a freelancer account. There is no self-serve way to switch it on. Plan details and prices are on the pricing page — visible without a sales call.
The documentation is the free part
The API guides and the full API reference are public with no signup wall, so the auth model, the endpoints, the async/callback model and the 4 requests/second limit are all inspectable before any commitment.
Translate files, not just strings
Create a project and send your file as a multipart request, then poll the project for status and export the translation when it’s done.
Long-running work is asynchronous by design — the API answers 202 IN PROGRESS — and you can register notification callbacks (webhooks, with custom headers) so your pipeline gets told instead of polling.
There is also a real-time endpoint when you genuinely do need a synchronous string back.
Translation memory, glossaries and human review
Segments your account has translated before are reused, and glossary terms are enforced — so a CI job translating release N+1 spends its linguistic effort only on what changed.
The same platform the API feeds includes review workflows and a marketplace of vetted linguists, a quality path a raw MT endpoint does not have.
There is also a Smartcat CLI intended for CI/CD pipelines, so a build step can push source files and pull translations without anyone writing an HTTP client.
1
Generate a key in Settings > API
As an administrator, open Settings > API. Your username is the string in the Account ID field; your password is an API key you create with CREATE NEW KEY. Multiple keys are allowed. This requires a company account on the Anticipate or Autonomous plan.
2
Send Basic auth on every call
Base64-encode accountId:apiKey and send it as the Authorization header. The API uses HTTP Basic authentication on every method.
3
Call your regional base URL
https://smartcat.ai/api/integration/v1/… for Europe, us.smartcat.ai for the Americas, ea.smartcat.ai for Asia. The documented quickstart is POST /api/integration/v1/project/create as a multipart request with your file. A public Postman collection is available on GitHub.
Why 4 requests per second is not a volume ceiling
Because the heavy operations are asynchronous (202 IN PROGRESS) and can call you back via webhooks, the rate limit caps request volume, not how much content you can put through.
How do API credentials work?
Credentials are per-account: an Account ID plus API keys you generate in Settings > API, and you can hold more than one key. The account must be a company account — the API cannot be used from a freelancer account.
Where does this fall short?
Plainly: the API is a paid-plan feature, it is not available on the free trial, and it needs a company account. If your requirement is a free API, forever, at any volume, Smartcat is the wrong choice and no landing page should tell you otherwise. Where it earns its price is recurring, multi-format, multi-language localization — the workload where TM reuse and review workflows outweigh per-call pricing.
A general MT API prices and processes per character, per call. That’s the right tool for translating one string at request time. It’s the wrong shape for localization: locale files have structure to preserve, product terms that must stay consistent, and huge overlap between releases that per-character pricing charges you for every time.
Smartcat’s API works at the file and project level: structure protection for JSON and XML, glossary enforcement, and translation memory reuse across every release and every format. The honest converse: if you need real-time, per-string translation inside a chat app, use an MT endpoint — that’s not this API’s job.
Supported languages
Rate limit, every method
File formats, no reduced API set
Type II compliant
Bring the formats you ship, your release cadence and your peak volume — 4 requests per second sizes very differently for nightly batches than for on-demand calls, and that’s the first thing we’ll work out with you. The 15-day platform trial exists if you want to see file translation in the UI; it just doesn’t include API access.
50%
increase in productivity
expondo increased productivity by 50% while reducing outsourcing costs by 50%, localizing in-house with Smartcat’s integrated platform.
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 time every month, time they can now use for more strategic work.
Smartcat is SOC 2 Type II compliant; content is encrypted in transit and at rest, and workspaces are isolated. Details on the security page.
The guides and the full API reference are public — read them before you talk to anyone. Access itself ships with Anticipate or Autonomous and a company account, which is why the next step is a conversation rather than a sign-up form.
What the call actually covers, in four parts:
It’s an engineer-facing 1:1 — bring your engineer and ours will be on the call.
No. It’s a paid feature of the Anticipate and Autonomous plans, and it is not included in the free trial. There is no free-forever tier, no free API key and no unlimited free usage.
Anticipate and Autonomous. It also requires a company account — the API cannot be used from a freelancer account. Plan details and prices are on the pricing page — visible without a sales call.
Not the API itself — it is not switched on for trial accounts. What you can do for free is read the public guides and API reference first, then bring your pipeline to a scoping call. The 15-day platform trial lets you see file translation in the UI, but it does not include API access.
The same 50+ formats the platform supports — there is no reduced API set. That covers: Office and OpenOffice documents, TXT and RTF; HTML, XHTML, PHP and JS; bilingual CAT formats (XLIFF 1.2 and 2.0, SDLXLIFF, MQXLIFF, PO, TTX); DTP files (PDF, MIF, INDD, IDML, CSV); DITA and Help+Manual XML; and software-localization resource formats (XML, Android XML, RESX, LOCJSON, JSON, TJSON, YML, INC, INX, STRINGS, PROPERTIES).
Executables and scripts are blocked for security.
4 requests per second, applied to every Smartcat API method. Exceed it and you get 429 TOO MANY REQUESTS. There is no per-plan differentiation, and it is documented publicly in the rate limits section of the API guides.
Because the heavy operations are asynchronous (202 IN PROGRESS) and can call you back via webhooks, 4 rps is a limit on request volume, not on how much content you can put through.
Public, at developers.smartcat.com, with no signup wall — API guides for the how-to and the API reference for the endpoint-by-endpoint detail.
Smartcat is SOC 2 Type II compliant; content is encrypted in transit and at rest, and workspaces are isolated. Credentials are per-account: an Account ID plus API keys you generate in Settings > API, and you can hold more than one key. Details on the security page.
Yes. A project can carry multiple target languages, and you export a translation per language. Because the heavy operations are asynchronous, your pipeline can register a notification callback rather than polling for each one.
There is a Smartcat CLI intended for CI/CD pipelines, so a build step can push source files and pull translations without anyone writing an HTTP client. Translation memory means release N+1 spends its linguistic effort only on what changed, and glossary terms stay enforced across releases.