cURL to Code Converter

How to Use the cURL to Code Converter

Paste a cURL command into the input area, select your target programming language from the dropdown, and click Convert. The tool parses the cURL command to extract the HTTP method, URL, headers, and request body, then generates equivalent code using the selected language's standard HTTP library. The stats panel shows the parsed method, URL, header count, and whether a body is present. Use the Copy button to copy the generated code to your clipboard.

This tool is invaluable for developers who test APIs with cURL and then need to integrate those requests into their application code. Browser developer tools let you copy any network request as a cURL command, making it easy to capture a working request and convert it to code in your language of choice.

Understanding cURL Commands

cURL is the most widely used command-line HTTP client, installed by default on virtually every operating system. A cURL command consists of the curl keyword followed by a URL and optional flags. The -X flag specifies the HTTP method (GET, POST, PUT, DELETE, etc.). The -H flag adds request headers like Content-Type and Authorization. The -d flag sends data in the request body. The -u flag provides basic authentication credentials.

When no method is explicitly specified, cURL defaults to GET. When the -d flag is used without -X, cURL automatically switches to POST. These implicit behaviors are preserved in the generated code, which explicitly sets the method to make the intent clear regardless of language-specific defaults.

Supported Languages and Libraries

The converter generates idiomatic code for four popular languages. Python code uses the requests library, which is the de facto standard for HTTP in Python. JavaScript code uses the built-in fetch API, which is available in all modern browsers and Node.js. Ruby code uses Net::HTTP from the standard library. PHP code uses cURL functions (curl_init, curl_setopt, curl_exec), which are available in virtually all PHP installations.

Handling Authentication and Headers

API requests often require authentication. The converter handles Bearer token authentication passed via -H 'Authorization: Bearer ...', Basic authentication via -u username:password, and API key headers. Custom headers are translated into the appropriate header-setting mechanism for each language. Content-Type headers are preserved to ensure the request body is sent in the correct format, whether JSON, form-encoded, or multipart.

Understanding cURL Flags

cURL offers dozens of command-line flags, but a handful account for the vast majority of real-world usage. Learning what each one does helps you read and write cURL commands confidently, and understanding them makes it easier to verify that converted code is correct.

Request Flags

The -X (or --request) flag sets the HTTP method. Common values are GET, POST, PUT, PATCH, and DELETE. If you omit -X entirely, cURL defaults to GET unless a data flag like -d is present, in which case it switches to POST automatically. The -H (or --header) flag appends a custom header to the request. You can use it multiple times to set several headers: -H 'Content-Type: application/json' -H 'Accept: application/json'. The -d (or --data) flag sends data in the request body and implies POST. For JSON payloads you typically pair it with -H 'Content-Type: application/json'. The variant --data-raw behaves identically but does not interpret the @ prefix as a file reference.

Authentication and Output Flags

The -u (or --user) flag provides Basic authentication credentials in the format username:password. cURL base64-encodes these and sends them in the Authorization header. The -o (or --output) flag writes the response body to a file instead of standard output. The -O flag saves to a file using the remote filename from the URL. The -v (or --verbose) flag prints detailed request and response information, including TLS handshake details and header exchanges, which is invaluable for debugging. The -k (or --insecure) flag tells cURL to skip TLS certificate verification, useful for development environments with self-signed certificates but dangerous in production. The -L (or --location) flag tells cURL to follow HTTP redirects (3xx responses), which many APIs and websites issue.

How the Conversion Works

Converting a cURL command to source code involves several discrete steps. The converter first tokenizes the input string, splitting it on whitespace while respecting single and double quotes so that header values and JSON bodies with spaces are kept intact. Next, it walks through the token list sequentially, identifying known flags and consuming their arguments. A flag like -X consumes the next token as the HTTP method; -H consumes the next token as a header string; -d or --data consumes the next token as the request body. Tokens that are not associated with any flag and look like URLs (starting with http:// or https://) are captured as the target URL.

Once parsing is complete, the converter holds a structured representation of the request: the URL, the HTTP method, a list of headers (each split into name and value on the first colon), the raw body string, and any authentication credentials. This intermediate representation is language-agnostic. The final step is code generation, where a language-specific template maps each component to the target language's HTTP idioms. The method becomes a function argument or a constant, headers become a dictionary or associative array, and the body is attached in the way the library expects. The generated code is formatted with proper indentation and ready to run.

Edge cases require special handling. Multiline cURL commands that use backslash continuation (\ at the end of a line) are joined before parsing. The -u flag is translated into a language-specific Basic auth mechanism rather than being left as a raw header. Duplicate headers are preserved in order, because some APIs rely on multiple values for the same header name (for example, multiple Set-Cookie headers). The converter also strips the leading $ or % shell prompt characters that sometimes appear when a command is copied from a tutorial or terminal screenshot.

Language-Specific HTTP Libraries

Each target language uses a different library with its own conventions for constructing HTTP requests. Understanding these differences helps you choose the right output and modify the generated code when needed.

Python — requests

The requests library is the most popular HTTP client in the Python ecosystem. It provides a simple, high-level API where the HTTP method maps directly to a function name: requests.get(), requests.post(), and so on. Headers are passed as a plain dictionary to the headers keyword argument. JSON bodies can be passed via the json parameter, which automatically sets the Content-Type header and serializes the dictionary. The auth parameter accepts a tuple for Basic authentication. Response data is available through .json(), .text, or .content depending on the desired format.

JavaScript — fetch API

The fetch API is built into all modern browsers and Node.js 18+. It takes a URL as its first argument and an options object as its second. The options object accepts method, headers, and body properties. Headers can be a plain object or a Headers instance. Unlike requests in Python, fetch does not throw on HTTP error status codes; you must check response.ok yourself. The response body is consumed asynchronously through methods like response.json() or response.text(). Because fetch returns a Promise, generated code uses async/await for readability.

Ruby — Net::HTTP

Ruby's standard library includes Net::HTTP, which is more verbose than the Python or JavaScript equivalents but requires no external dependencies. A typical request starts by parsing the URL into a URI object, then creating an Net::HTTP instance configured for the host and port. Request objects like Net::HTTP::Post or Net::HTTP::Get represent the method. Headers are set using bracket notation on the request object. The body is assigned directly. For HTTPS URLs, use_ssl must be set to true. Because of this ceremony, many Ruby developers use wrapper gems like Faraday or HTTParty, but generated code sticks to the standard library for maximum portability.

PHP — cURL Extension

PHP's cURL extension wraps the same libcurl library that powers the command-line curl tool. The workflow revolves around a handle created with curl_init(). Options are set via curl_setopt() calls: CURLOPT_URL for the target URL, CURLOPT_CUSTOMREQUEST for the HTTP method, CURLOPT_HTTPHEADER for an array of header strings, and CURLOPT_POSTFIELDS for the request body. Setting CURLOPT_RETURNTRANSFER to true makes curl_exec() return the response as a string instead of printing it. Because the PHP extension mirrors libcurl's C API closely, the generated PHP code maps almost one-to-one with the original cURL flags, making it the most transparent conversion of the four languages.

Frequently Asked Questions

What is cURL?

cURL is a command-line tool for making HTTP requests. It is pre-installed on Linux, macOS, and Windows 10+, and is the standard tool for testing APIs.

How do I read a cURL command?

It starts with curl followed by a URL. Use -X for method, -H for headers, -d for body data, and -u for authentication.

What HTTP methods does cURL support?

All standard methods: GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS. Set the method with the -X flag.

Can I convert cURL with authentication?

Yes. The tool handles Basic auth (-u), Bearer tokens (-H Authorization), and other header-based auth patterns.

Does this handle multipart form data?

Yes. Commands with -F flags for file uploads and form fields are converted to the appropriate multipart syntax in each language.