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Readable command output
Build a multiline cURL command that is easier to review, copy, document, and debug.
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cURL Builder
Build secure cURL commands for HTTP requests with methods, headers, query parameters, authentication, and request bodies.
GET, POST, PUT, PATCH, DELETE, HEAD, and OPTIONS methods Query parameter encoding Custom request headers Bearer, Basic, and API key authentication
Review generated commands before running them. Avoid pasting production secrets into shared devices, screenshots, logs, or support messages.
Private browser processing. Your input is processed on this device and is not sent to the Trexmi server.
INPUT Request URL *
Generated cURL command
Shell-safe cURL command ready to review and copy.
About the tool
What cURL Builder does
cURL Builder is a powerful online cURL command generator for developers, QA engineers, API testers, technical writers, and support teams. It turns a structured HTTP request into a readable shell command without forcing you to remember every cURL option. Configure the endpoint, request method, query parameters, headers, authentication, body type, redirects, and compression, then copy the generated command.
The cURL Builder supports common REST API workflows such as GET requests with search parameters, authenticated POST requests with JSON, form submissions, PATCH updates, DELETE calls, and header-based API keys. Query names and values are URL encoded automatically. Header lines are validated before they are added, and JSON request bodies are parsed before output so malformed JSON is caught early.
Generated commands use shell-safe quoting for values. Even so, always review the result before execution. Access tokens, passwords, private API keys, session cookies, and customer data should not be shared in screenshots, issue trackers, chat messages, analytics, or public command history.
How to use
- Enter the request URL. Use a complete HTTP or HTTPS endpoint.
- Select the HTTP method. GET reads data, while POST, PUT, PATCH, and DELETE commonly change server state.
- Add query parameters. Enter one name=value pair per line.
- Add request headers. Use one Header-Name: value line for each header.
- Configure authentication. Choose Bearer, Basic, API key, or no authentication.
- Add the request body. Select JSON, form, text, XML, or no content type.
- Generate and review. Confirm the URL, method, credentials, headers, and body before running the command.
Built for the task
Why use cURL Builder?
Focused controls, predictable output, and a workflow designed around this exact transformation.
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Safer value quoting
Headers, credentials, body content, and the final URL use shell-safe single-quoted values.
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Complete HTTP configuration
Combine methods, parameters, headers, authentication, redirects, compression, and body content.
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Input validation
Catch invalid URLs, malformed headers, incomplete authentication values, and invalid JSON before execution.
Useful answers
Questions about cURL Builder
Practical details about input, output, privacy, limits, and the best way to use this tool.
01 What is cURL Builder?
cURL Builder is an online tool that converts HTTP request settings into a cURL shell command. It supports methods, query parameters, headers, authentication, bodies, redirects, and compressed responses.
02 Does cURL Builder send the HTTP request?
No. It generates a command for review and copying. The request is sent only when you run the resulting command in your own terminal or environment.
03 Can I generate a POST request with JSON?
Yes. Choose POST, select JSON as the content type, and paste a valid JSON body. The builder adds the Content-Type header when one is not already present.
04 How are query parameters added?
Enter one name=value pair per line. The builder URL encodes names and values and appends them to the endpoint using the correct question mark or ampersand separator.
05 Which authentication modes are supported?
The tool supports Bearer tokens, Basic username:password authentication, API key headers, and requests without authentication.
06 Can I add custom headers?
Yes. Enter one Header-Name: value pair per line. Invalid header names and incomplete lines are rejected.
07 Is the generated command safe to share?
Not automatically. Generated commands may contain passwords, tokens, cookies, API keys, private URLs, or personal data. Remove secrets before sharing.
08 Why is the command split across several lines?
Multiline output is easier to inspect and edit. Backslashes continue the same shell command on the next line.
09 Does it support Windows Command Prompt?
The generated output targets common POSIX-style shells such as Bash and Zsh. PowerShell and Windows Command Prompt use different quoting and line-continuation rules.
10 Why validate JSON before generating cURL?
Malformed JSON is a common cause of failed API requests. Early validation prevents creating a command that sends an invalid JSON document.
Learn HTTP & Network Debugging
Read the HTTP Headers Guide
Connect DNS, redirects, HTTP headers, requests, responses, caching, security, and practical web diagnostics.
- Requests and response headers
- Redirect and cache diagnostics
- Security and API debugging
Read guide
Practical explanations and examples
How cURL Builder works online
The cURL Builder reads the request URL and validates that it uses HTTP or HTTPS. It then applies URL-encoded query parameters, validates header syntax, adds selected authentication, checks the request body, and produces a command. Values are quoted separately so spaces and many shell metacharacters remain part of the intended value.
The builder does not contact the endpoint. This separation lets you inspect the request before execution and makes the result suitable for API documentation, bug reports, terminal testing, and reproducible support instructions.
cURL Builder HTTP methods
GET
Use GET to retrieve resources without intentionally changing server state. Query parameters commonly control search, filtering, sorting, and pagination.
POST
Use POST to create resources, submit forms, start jobs, or perform actions defined by an API.
PUT and PATCH
PUT commonly replaces a complete resource, while PATCH commonly applies a partial update. Actual behavior depends on the API specification.
DELETE
DELETE requests can permanently remove or deactivate data. Review the endpoint and authentication carefully before execution.
cURL Builder headers and authentication
Headers communicate accepted response formats, content types, conditional request values, request identifiers, authorization credentials, and vendor-specific options. Add only headers required by the target API. Duplicate or contradictory headers can cause confusing server behavior.
Bearer authentication creates an Authorization: Bearer value. Basic authentication uses cURL user credentials. API key mode accepts a custom header name and value because APIs use different names such as X-API-Key or Api-Key.
cURL Builder request bodies and content types
JSON is common for REST APIs. Form URL encoded content is common for traditional forms and OAuth token endpoints. Plain text and XML remain useful for specialized integrations. A body can technically be sent with several methods, but the server decides whether it is accepted.
When JSON is selected, cURL Builder verifies that the body is valid JSON. This validation checks syntax only; it does not confirm required fields, business rules, or JSON Schema constraints.
Practical cURL Builder examples
GET with query parameters
curl -L --compressed 'https://api.example.com/v1/users?page=1&limit=20'POST JSON
curl -L --compressed -X POST -H 'Content-Type: application/json' --data-raw '{"name":"Trexmi"}' 'https://api.example.com/v1/users'Bearer token
curl -L --compressed -H 'Authorization: Bearer TOKEN' 'https://api.example.com/v1/profile'Custom API key
curl -L --compressed -H 'X-API-Key: SECRET' 'https://api.example.com/v1/reports'Common cURL Builder errors
Invalid URL
Include the protocol and a valid hostname. Relative paths are not complete request targets.
Malformed headers
Each custom header requires a colon between its name and value. Do not paste line breaks inside a header value.
Incorrect Content-Type
The declared type must match the body format. Sending JSON while declaring form data can make the server reject or misread the request.
Authentication failures
Confirm token scope, expiration, environment, header name, username, and password. A correct cURL command cannot make invalid credentials valid.
Shell quoting differences
The generated command targets POSIX-style shells. Translate quoting and continuation rules before using it in PowerShell or Command Prompt.
10-point cURL Builder security checklist
Use test accounts where possible. Remove credentials from terminal history. Do not commit commands containing secrets. Avoid disabling TLS verification. Confirm destructive methods and production hosts. Redact Authorization, Cookie, Set-Cookie, and API key values before sharing output.
Related Trexmi tools
Look up server responses with HTTP Status Code Lookup, inspect URL parameters with Query String Parser, and prepare API payloads with JSON Formatter.
Authoritative cURL references
Review the official cURL command-line documentation and the MDN HTTP method reference when building production requests.