Practical developer formatting guides

Regex Matcher GuideHow to test patterns, parser behavior, flags and capture groups without over-trusting one match. Regex ExamplesPractical JavaScript regex patterns for email, URL, UUID, slugs, colors, dates and logs. Email Regex ValidatorUse email regex as a practical format check, not a complete deliverability test. URL Regex ValidatorValidate simple link shape and learn when URL parsing is safer. UUID v4 RegexCheck version and variant characters in API identifiers and log values. Date Regex ValidatorValidate YYYY-MM-DD string shape before using a calendar parser. Regex Log ParserCapture log timestamps, levels and messages during incident debugging. XML Linter GuideCommon xmllint-style errors, well-formed XML rules and when XSD validation is still needed. API Debugging GuideHow to debug status codes, auth, payloads, schemas, logs and retries. HTTP Status Codes ReferenceSearch response codes and connect them to practical API debugging checks. HTTP Headers ReferenceUse headers to debug auth, CORS, cache and browser security behavior. JSON Formatting GuideHow to read, validate and safely share JSON payloads. JSON Schema GuideHow to review generated schemas, required fields and array item rules. YAML Indentation GuideWhy YAML indentation fails and how to review nested config blocks safely. YAML Formatting GuideWhy indentation matters and how to avoid config mistakes. SQL Cleanup GuideHow to clean query snippets so joins, filters and clause boundaries are easier to inspect. SQL Formatting GuideHow readable SQL helps reviews, debugging and performance conversations. Python Indentation GuideWhen Python indentation errors happen and what a browser cleanup can safely change. Safe Online Developer ToolsWhat not to paste into any web tool and how Formalint handles input.