DeepL Write API for Pro Users Documentation

Your comprehensive guide to accessing and utilizing DeepL Write API features

Key Highlights

DeepL Write API Overview and Access – Understand the API’s purpose, endpoints, and access restrictions for Pro users.
Request and Response Details – Learn about the required parameters, request formats, and response structures.
Documentation and Integration Resources – Find official documentation links, client libraries, and guidelines for implementation.

Introduction

The DeepL Write API for Pro users is specifically designed to help professionals enhance and refine text through rephrasing and improvements. As an integral part of the broader DeepL API Pro offering, this API provides advanced linguistic technology to elevate your writing. Whether you are a developer integrating language enhancements into your applications or a professional seeking an automated text improvement solution, understanding the DeepL Write API documentation is essential. This guide compiles all the necessary documentation details, usage instructions, and resource links to help you operate the API with maximum efficiency.

API Overview and Access

DeepL Write API Purpose

The DeepL Write API is dedicated to improving text quality, offering features such as text rephrasing and language style optimization. This functionality is exclusively available to DeepL API Pro users, ensuring enhanced security, scalability, and support. The API is hosted on an HTTP interface and is accessible via the endpoint:

Endpoint

Endpoint: /write/rephrase

This endpoint handles requests to refine provided text and returns the improved version alongside language details. It is important to note that only users with a valid DeepL API Pro subscription have access to these advanced text improvement capabilities—free API users do not have access to these features.

Authentication and API Keys

To interact with the DeepL Write API, you must generate and use API keys identical to those used with other DeepL API endpoints. Pro users have access to up to 25 active API keys simultaneously. When making a request, include your authentication key in the HTTP header to ensure secure access.

The authentication process is documented in detail on the official DeepL website. Always ensure that your API key is kept secure and that you follow best practices for key management to prevent unauthorized access.

Request Format and Parameters

Supported Request Formats

The DeepL Write API accepts both form-encoded and JSON-encoded request bodies. This flexibility allows developers to choose the format that best aligns with their application needs. The request must be made over HTTPS, ensuring that your communication with DeepL remains secure.

Essential Request Parameters

The API documentation specifies several key parameters that must be included in each request. The main parameters include:

Text Parameter

Parameter: text
Description: This parameter is required. It represents the plain text (in UTF-8 encoding) that you want to improve or rephrase. The text can contain multiple sentences, and the API maintains the order of improvements corresponding to the input.

Target Language

Parameter: target_lang
Description: This optional parameter dictates the language in which the improved text will be delivered. Supported language codes include:

de (German)
en-GB and en-US (British and American English)
es (Spanish)
fr (French)
it (Italian)
pt-BR and pt-PT (Brazilian Portuguese and European Portuguese)

It is crucial that the source text is provided in a language compatible with the target language parameter.

Example Request Body

Below is an illustrative example of a JSON-encoded request body using the /write/rephrase endpoint:


{
    "text": "Your original sentence that needs improvement.",
    "target_lang": "en-US"
}

Similarly, if using the form-encoded format, ensure that the parameters are correctly passed as form fields.

Response Structure and Error Handling

Standard Response Format

The API responds with a JSON object that primarily includes a key called improvements. This key holds an array of objects, where each object contains the following fields:

text: The improved text.
target_language: The language of the improved text.
detected_source_language: The language detected from the original text.

These fields ensure that you receive both the refined text and useful metadata regarding the text transformation process.

Error Response Management

Error handling is a critical aspect of the DeepL Write API. When a request fails, the API returns an appropriate HTTP status code along with a descriptive error message in the JSON response. Common issues might include:

Invalid API key or authentication failure
Malformed request bodies or missing required parameters
Exceeding character limits as set by your plan

For a detailed breakdown of potential errors and how to resolve them, refer to the official DeepL error code documentation available on the DeepL website.

Integration and Client Libraries

Available Client Libraries

To facilitate a seamless integration, DeepL offers client libraries for various programming languages such as Python, JavaScript, .NET, PHP, Java, and Ruby. These libraries are designed to abstract much of the complexity involved with direct API calls, making it easier to incorporate text improvement functionalities into your projects.

For example, Python developers can use the DeepL Python library that includes methods such as rephrase_text() to interface with the API. These libraries also often include built-in support for setting parameters, handling authentication, and managing responses.

Scalability and Usage Limits

The DeepL Write API is built to scale with the needs of professional users. According to your subscription plan, there are specific character limits which govern the volume of text that can be processed. In addition, deep integration into automated workflows, web applications, and other internal tools is possible, enhancing overall productivity.

It’s important to manage usage and monitor character consumption, especially when integrating the API into high-traffic applications, to control costs and ensure uninterrupted service.

In-Depth Technical Documentation

Documentation Overview

The comprehensive documentation available for the DeepL Write API covers everything from authentication, request formatting, parameter descriptions, to response and error details. This documentation is continually updated to reflect new features and optimizations.

Whether you are a first-time user looking to understand the basics or a seasoned developer integrating advanced features into your systems, the official documentation serves as your go-to resource.

Table of Key API Features

Feature	Description	Details
Endpoint	Rephrasing and text improvement	Accessible via `/write/rephrase`
Request Format	Form-encoded or JSON-encoded	Supports both request types for flexibility
Authentication	API Key	Requires a valid DeepL API Pro subscription key
Required Parameters	Text input, language options	Must include `text` and optionally `target_lang`
Response Format	JSON response	Includes improved text and language metadata
Error Handling	HTTP status codes	Returns detailed error messages in JSON format
Client Libraries	Python, JavaScript, and more	Facilitates easy integration and development

Additional Resources and Documentation Links

Official DeepL Documentation Links

For the most updated information and extended documentation details, please refer to the following official resources provided by DeepL:

Additional Integration Resources

To further ease the integration of the DeepL Write API into your projects, consider exploring the following:

Detailed error management and troubleshooting guides available on the DeepL website.
Tutorials and sample code provided within the client library documentation for multiple programming languages.
Community forums and support channels where developers discuss best practices and share integration experiences.

Best Practices for Utilizing the DeepL Write API

Securing Your API Keys

It is imperative to treat your API keys as sensitive credentials. Always avoid hardcoding these values in your application code and use secure storage solutions. Regularly review and update your keys, limiting their exposure by managing access permissions and rotation policies.

Monitoring and Scalability

Ensure that you keep track of your usage, particularly if your application processes a high volume of text. Set appropriate character limits and monitor API requests to avoid unexpectedly high costs. Employ logging and error tracking to maintain a robust integration and quickly address any connectivity or performance issues.

Integration Testing and Debugging

Before deploying your application on a production environment, perform comprehensive integration testing. Use sandbox or test environments provided by DeepL to simulate requests and evaluate responses. This proactive approach will assist you in identifying potential issues early and implementing effective debugging strategies.

Summary of DeepL Write API Features

Feature Overview

The DeepL Write API is a specialized tool that provides professional-grade text improvement functionalities through a simplified HTTP interface. Key elements include:

A dedicated rephrasing endpoint (/write/rephrase) which accepts both form-encoded and JSON-encoded requests.
A robust response format that includes improved text and language metadata, ensuring clarity in the delivered output.
Detailed error management to assist in troubleshooting and ensuring smooth integration.
Extensive documentation and client libraries that cover popular programming languages for effortless API usage.
Secure access practices via API key management aligned with the Pro subscription benefits.