Online Curl Validator

The online curl validator solves the problem of validating curl commands before they are executed in production, CI pipelines, or shared code samples. It targets API developers, integration engineers, QA testers, and learners who craft curl invocations for testing or debugging. By entering a curl command, users receive immediate feedback on syntax, URL validity, HTTP method, headers, and data payload, with any conflicts or missing components highlighted. It also normalizes varied curl forms into a canonical representation suitable for scripting. Core value: reduced failed requests, faster debugging, and improved reproducibility in API work.
Core Logic & Features: The tool performs lexical parsing of curl tokens, rule-based checks for options, and domain-specific validations (URL scheme, host, header formatting, data encoding). Required features include syntax verification, header and data validation, and canonicalization. Optional/advanced features include JSON payload validation, support for multiple -H headers, and detection of conflicting flags. The system emits a structured diagnostic with error codes and a cleaned curl string suitable for scripting.
Inputs & Outputs: Input is a single curl_command string. Output includes a diagnostic object (errors, warnings, suggested fixes) and a canonical curl string. Validation rules cover URL format (http/https), proper quoting, consistent headers, and payload encoding. Outputs are designed for both human readability and machine consumption, enabling downstream automation.
Algorithms & Calculations: The validator uses lexical tokenization, pattern matching for common curl flags (-X, -H, -d, --data-raw, --url), and rule-based validation (URL validity, header syntax, payload type matching with Content-Type). It derives a canonical form by normalizing flag order and payload encoding, while preserving semantic meaning.
Error & Edge Cases: Handles missing command, malformed URL, unsupported options, conflicting -d and -G usage, or JSON payloads with invalid syntax. Incomplete headers or data deliver a specific warning with remediation steps. Large or complex curl commands are parsed in a streaming fashion to avoid performance degradation.
Industry/Region & Localization: Assumes POSIX-compatible curl behavior and standard HTTP/HTTPS semantics. No locale-sensitive data; outputs and messages are in English by default and suitable for translation if needed.
Assumptions & Exclusions: Assumes input is a single curl invocation without shell-specific expansions or aliases. Excludes UI or interactive features; focused on command-level validation and canonicalization for developers and automation.