✓ Checked against DeepL's official pages on 23 September 2026. Screens and prices change: if something looks different, trust what DeepL shows you.
A DeepL API key is a secret code that lets TranslateRocket send your site’s text to DeepL, a translation service known for natural-sounding results, and get the translation back; DeepL has a free plan to start and paid plans for more text.
📖 Words you will meet
- API key: a long secret code. Whoever has it can use your DeepL allowance, so treat it like a password.
- DeepL API: the version of DeepL for websites and apps. It is a different product from the DeepL Translator subscription (DeepL Pro for people): that subscription does not give you an API key.
- Characters: DeepL charges by the number of characters in your original text, spaces included.
Which DeepL API plan?
Prices shown on DeepL’s plans page for Italy, in euro, VAT included, on 23 Sep 2026. Other countries may see other amounts.
| Plan | Price | What you get |
|---|---|---|
| Developer | Free | 1,000,000 characters in total, once. It does not reset every month: when it is used up, you must upgrade. One API key. |
| Growth | €29.75 per month (monthly billing), or €23.80 per month billed yearly | Monthly: 1 million characters included per month. Yearly: 12 million characters per year. Extra characters: €22.00 per 1,000,000. Your texts are not used to train DeepL’s models. |
| Enterprise | On request | For large companies. |
If you signed up years ago you may be on an older plan called DeepL API Free (500,000 characters per month) or DeepL API Pro. They still work, and this guide applies to them too.
What you need before you start
- An email address.
- For the Developer plan: no card. DeepL’s developer page says “Start free, no credit card required.”
- For the Growth plan: a payment card.
- If you already have a DeepL account for the online translator, DeepL says you must log out and create a new account for the API.
- About 5 minutes.
Step by step
TranslateRocket – mysite.com) and click Create key again to confirm.Keep the key somewhere safe until you paste it into WordPress (a password manager is ideal). Do not send it by email or chat.
How much it costs
DeepL counts the characters of your original text, spaces included. HTML code is not counted.
What that means for a small site. Our example: a site of 20 pages with about 600 words each (12,000 words), which is about 75,000 characters.
- Developer plan (free): one language uses about 75,000 of your 1,000,000 characters. So the free allowance covers this site in about 13 languages in total, once. After that you need Growth.
- Growth plan: the 1 million characters included each month cover the same site in about 13 languages per month. Above that, each extra language costs about 75,000 × €22 / 1,000,000 ≈ €1.65.
Remember: every language is counted separately. Translating the site into Italian and German uses the characters twice. Text that TranslateRocket has already translated is reused and not sent again.
Safety (please read)
1. On the Developer plan you cannot be charged. When the 1,000,000 characters are used up, DeepL simply stops translating.
2. On a paid plan, set a limit. DeepL gives you two.
- Whole account (“Cost Control”):
1. Open the API Usage tab: https://www.deepl.com/your-account/usage
2. Click the link to change cost control settings for characters.
3. Tick the box to activate the limit.
4. Enter the maximum number of characters per month (for example
1000000, the amount included in Growth, so you never pay extra). 5. Click Submit. - Per key: in the API Keys & Limits tab, open the key’s options menu, choose Set limit, activate it, choose characters and enter an amount.
DeepL emails you at 80% and 100% of a limit, and then stops translating until the next period.
3. Set a limit inside TranslateRocket too. In TranslateRocket → AI Translation, section Usage & limits, fill in Daily character limit (for example 200000). When the limit is reached, automatic translation stops until the next day. 0 means no limit.
4. Never share the key. Do not put it in emails, chats, screenshots or support tickets.
5. If you think the key has leaked, deactivate it.
- Open https://www.deepl.com/your-account/keys
- On the Developer plan you can have only one active key, so first deactivate the old one: click the more options icon next to the key, choose Deactivate key, and confirm. (On paid plans, create the new key first, then deactivate the old one.)
- Click Create key and paste the new key into TranslateRocket.
Deactivation is immediate and permanent: a deactivated key cannot be switched back on. DeepL also advises changing your DeepL account password if you suspect misuse.
Where to paste it in TranslateRocket
- In your WordPress dashboard, open TranslateRocket → AI Translation.
- In the Provider & keys box, find the card called DeepL.
- Paste your key into the API key field.
- At the top of the box, set Active provider to DeepL.
- Click Save AI settings at the bottom of the page.
- Back on the DeepL card, click Check usage: it asks DeepL how many characters you have used. If you see a number, the key works.
DeepL has no “model” to choose. The House style instructions on the same page only work with the AI models (OpenAI, Claude, Gemini); DeepL ignores them.
If something does not work
| What you see | What it usually means | What to do |
|---|---|---|
| “Could not reach DeepL — check the key”, or error 403 | The key was copied wrongly, or it was deactivated. | Paste it again carefully; copy it again from API Keys & Limits with the copy icon. If it was deactivated, create a new one. |
| Error 456, or “the monthly character allowance is used up” | Your characters are finished: the Developer plan’s 1,000,000 (which never resets), or your Cost Control limit. | Click Check usage to see the numbers. Upgrade to Growth, raise your Cost Control limit, or wait for the next period. |
| Error 429 | Too many requests in a short time. | Wait a minute and try again. |
TranslateRocket may also show: DeepL refused with “quota exceeded”, but your account still reports … characters used. In that case the allowance is not the problem: log in at https://www.deepl.com/your-account and check that your account and payment details are in order, or contact DeepL support.
Questions people ask
Is the DeepL API free?
The Developer plan is free and needs no card: it gives 1,000,000 characters in total, once. It does not reset every month. The Growth plan adds 1 million characters per month.
Does a DeepL Pro subscription include an API key?
No. The DeepL Translator subscription is a different product. DeepL says that if you already have an account for the online translator, you must create a new account for the API.
What does ":fx" at the end of a DeepL key mean?
Keys ending in ":fx" are free-plan keys and use DeepL's free server. TranslateRocket reads the ending and picks the right server for you.
How many DeepL characters does a website use?
DeepL counts the characters of your original text, spaces included, not HTML. A site of 20 pages with about 600 words each is about 75,000 characters per language.
Which one should I choose?
See our comparison page for a simple comparison of all five services, and for the free option that needs no key at all.
Other guides: OpenAI · Anthropic (Claude) · Google Gemini · Google Cloud Translation · Which one should I choose?
