DeepLX-Lib

🌍 Powerful free DeepL API wrapper with no token required. Easily integrate DeepLX into any application.

Features

• 📦 Zero dependencies, extremely lightweight
• 🌐 Supports all DeepL languages (including variants like EN-GB, ZH-HANS)
• 💡 Automatically constructs jsonrpc request bodies, mimicking browser behavior
• 🧪 Fully tested with unit tests for reliability

Installation

npm i deeplx-lib
# or
pnpm add deeplx-lib
# or
yarn add deeplx-lib

Usage

import { translate } from 'deeplx-lib'

const result = await translate({
  from: 'EN',
  to: 'ZH',
  text: 'Hello, world!',
})

const data = await result.json()
console.log(data)
/*
{
  jsonrpc: '2.0',
  id: 123456789,
  result: {
    texts: [
      {
        alternatives: [ { text: '世界，你好' }, { text: '你好，世界！' }, { text: '大家好' } ],
        text: '你好，世界'
      }
    ],
    lang: 'EN',
    lang_is_confident: false,
    detectedLanguages: {
      EN: 0.48555099999999995,
      DE: 0.038853,
      FR: 0.003078,
      ES: 0.008555,
      PT: 0.0049429999999999995,
      IT: 0.016312,
      NL: 0.061256,
      PL: 0.017636,
      RU: 0.0004969999999999999,
      ZH: 0.0036209999999999997,
      JA: 0.000523,
      BG: 0.00007099999999999999,
      CS: 0.009665,
      DA: 0.0034609999999999997,
      EL: 0.00016099999999999998,
      ET: 0.008915,
      FI: 0.002085,
      HU: 0.004044,
      LT: 0.00029099999999999997,
      LV: 0.001053,
      RO: 0.004389,
      SK: 0.002541,
      SL: 0.00106,
      SV: 0.002949,
      TR: 0.00075,
      ID: 0.005395,
      UK: 0.00010899999999999999,
      KO: 0.006984,
      NB: 0.042485999999999996,
      AR: 0.000068,
      VI: 0.001168,
      HE: 0.000098,
      unsupported: 0.26143
    }
  }
}
*/

API

translate(options: IOptions): Promise<Response>

Send a translation request to DeepL's internal JSON-RPC endpoint.

Parameters

Name	Type	Description
from	TSourceLanguage	Source language
to	TTargetLanguage	Target language
text	string	Text to translate

parse2DeepLX(data: IOptions & IDeepLData): IDeepLXData

Parses the raw DeepL JSON-RPC response into a simplified, standardized format for easier usage.

Useful when you want to normalize the translate or fetch result into a consistent structure.

Example

import { parse2DeepLX, translate } from 'deeplx-lib'

const translateData: IOptions = {
  from: 'EN',
  to: 'ZH',
  text: 'Good morning',
}

const response = await translate(translateData)

const raw = (await response.json()) as IDeepLData
const normalized = parse2DeepLX({
  ...translateData,
  ...raw,
})

console.log(normalized)
/*
{
  code: 200,
  id: 123456789,
  method: 'Free',
  from: 'EN',
  to: 'ZH',
  source_lang: 'EN',
  target_lang: 'ZH',
  data: '早上好',
  alternatives: ['早安', '上午好']
}
*/

getBody(options: IOptions): string

Generates a JSON-RPC-compliant request body that mimics DeepL’s internal format. You can use it to manually perform the request using your own fetch implementation.

Example

import { DEEPL_URL, getBody } from 'deeplx-lib'

const body = getBody({
  from: 'EN',
  to: 'ZH',
  text: 'Hello, world!',
})

const response = await fetch(DEEPL_URL, {
  method: 'POST',
  body,
  headers: { 'Content-Type': 'application/json' },
})

const result = await response.json()
console.log(result) // The result is the same as `translate(options: IOptions)`

Language Types

// Subsequent changes may be made, see details at: https://github.com/lete114/deeplx-lib/blob/main/src/types.d.ts
export type TVariant = 'EN-GB' | 'EN-US' | 'PT-BR' | 'PT-PT' | 'ZH-HANS' | 'ZH-HANT'
export type TLanguage =
  | 'AR' | 'BG' | 'CS' | 'DA' | 'DE' | 'EL' | 'EN' | 'ES' | 'ET'
  | 'FI' | 'FR' | 'HU' | 'ID' | 'IT' | 'JA' | 'KO' | 'LT' | 'LV' | 'NB'
  | 'NL' | 'PL' | 'PT' | 'RO' | 'RU' | 'SK' | 'SL' | 'SV' | 'TR' | 'UK' | 'ZH'
export type TSourceLanguage = 'AUTO' | TLanguage
export type TTargetLanguage = TLanguage | TVariant

export interface IOptions {
  from: TSourceLanguage
  to: TTargetLanguage
  text: string
}

Other Exports

Method	Description
parse2DeepLX	Parses the full DeepL response into a DeepLX format
getBody	Constructs the JSON-RPC request body
getICount	Counts the number of "i" characters in the text
getTimestamp	Generates a timestamp adjusted by the text content
getRandomNumber	Generates a pseudo-random request ID
handlerBodyMethod	Modifies the method field to emulate client format

Testing

Unit tests are written using Vitest. Run the tests with:

pnpm test

License

MIT License © Lete114

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