cURL Converter

Comparison of cURL conversion tools measuring parsing accuracy and conversion speed across 100 test cases with varying complexity.

Learn the fundamentals of cURL, from basic GET requests to complex POST operations with headers, authentication, and data payloads.

Why Convert cURL Commands?

cURL is the universal language of HTTP requests. When API documentation provides examples, they almost always include a cURL command. When developers share troubleshooting steps, they use cURL. When you copy a request from Chrome DevTools, it gives you cURL. But most applications are not written in bash. You need that request in JavaScript, Python, Go, or whatever language your project uses.

Manually translating a cURL command to your programming language is tedious and error-prone. Headers need to be reformatted, data payloads need different escaping, authentication schemes need language-specific implementations. A single missed header or incorrectly formatted body can mean hours of debugging. The cURL converter eliminates this friction by parsing the command and generating idiomatic code for your target language.

This tool is particularly valuable when working with APIs that have complex authentication flows, multiple headers, or nested JSON payloads. Instead of manually constructing the request object in your language, you can test with cURL first, verify it works, then convert to production code with confidence that the request parameters are identical.

Understanding cURL Flags

The cURL command-line tool supports over 200 flags, but most API interactions use a core set. The -X flag specifies the HTTP method (GET, POST, PUT, DELETE, PATCH). Without -X, cURL defaults to GET unless data is provided with -d, which implies POST. The -H flag adds HTTP headers, and you can include multiple -H flags for multiple headers.

The -d flag sends data in the request body. By default, cURL sends this as application/x-www-form-urlencoded, but when combined with a Content-Type: application/json header, the data is sent as JSON. The --data-urlencode flag is similar but automatically URL-encodes the value, which is useful for form submissions with special characters.

Authentication in cURL uses the -u flag for basic authentication (username:password format) and can also be handled through Authorization headers. The -b flag sends cookies, -k disables SSL certificate verification (useful for development with self-signed certificates), and --compressed tells the server that the client accepts compressed responses.

JavaScript Fetch API Conversion

The Fetch API is the modern standard for making HTTP requests in JavaScript. When converting cURL to fetch, the URL becomes the first argument, and all options (method, headers, body) are passed as the second argument in an options object. Headers are represented as a plain object or Headers instance, and the request body is passed as a string.

One important difference between cURL and fetch is error handling. cURL treats any HTTP response as successful (even 4xx and 5xx status codes), while fetch only rejects on network errors. The generated code includes a response.ok check to handle HTTP error status codes properly. For JSON responses, the code chains .json() to parse the response body.

The converter also handles the async nature of fetch. Since fetch returns a Promise, the generated code uses async/await syntax for readability. This matches the modern JavaScript convention used in most codebases and frameworks.

Python Requests Conversion

The Python requests library is the de facto standard for HTTP requests in Python. The conversion maps cURL flags to requests parameters: -X becomes the method, -H headers become a dictionary, -d data becomes either the data or json parameter depending on Content-Type, and -u becomes the auth tuple.

The requests library handles many details automatically that cURL requires explicit flags for. Compressed responses are decompressed by default, JSON responses can be parsed with response.json(), and session management handles cookies across multiple requests. The generated code takes advantage of these conveniences while maintaining the exact same request as the original cURL command.

Converting to PHP, Go, Ruby, Java, and C#

Each target language has its own idiomatic way of making HTTP requests. PHP uses the built-in cURL extension (curl_init, curl_setopt, curl_exec), which mirrors the command-line tool closely. Go uses the net/http package with explicit request construction and client execution. Ruby uses Net::HTTP from the standard library with URI parsing and request objects.

Java conversion targets the HttpClient API introduced in Java 11, which provides a modern, fluent interface for HTTP requests. C# uses System.Net.Http.HttpClient, which is the recommended approach for .NET applications. Both Java and C# conversions include proper resource management and exception handling patterns expected in enterprise codebases.

The Node.js output uses axios, the most popular HTTP client for Node.js with over 40 million weekly npm downloads. Axios provides a cleaner API than the built-in http module, with automatic JSON parsing, request/response interceptors, and better error handling. The generated code uses the config object pattern that axios developers expect.

Reverse Mode: Code to cURL

Sometimes you need to go the other direction. You have a fetch() call or requests.post() in your code, and you need to reproduce the exact request as a cURL command for debugging, sharing with teammates, or pasting into documentation. The reverse mode parses JavaScript fetch and Python requests code and generates the equivalent cURL command.

This feature is particularly useful when debugging API issues. You can take the exact request your application makes, convert it to cURL, run it in your terminal to verify it works outside the application context, then modify parameters to isolate the issue. The reverse conversion preserves all headers, authentication, and body data from the original code.

Security Considerations

cURL commands often contain sensitive data: API keys, authentication tokens, passwords, and private endpoint URLs. This converter runs entirely in your browser. No data is transmitted to any server, no requests are logged, and no cookies are set. Your cURL commands and API credentials stay on your device.

When sharing converted code, always review the output for hardcoded credentials. Best practice is to replace sensitive values with environment variables or configuration references before committing code to version control. The generated code can serve as a template that you modify to use your application's configuration management system.

Compatibility data sourced from caniuse.com.