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These articles are static pages built from Markdown in the repository. They explain concepts and point to tools that run locally in your browser whenever the task allows.
Reading a JWT without trusting the server
How JWT structure, Base64URL encoding, and signatures work — and why decoding locally beats pasting tokens into random websites.
Published: 2026-07-20
Read article →Cron expressions for humans
How five-field cron syntax maps to minutes, hours, days, and months — plus common patterns for backups, reports, and jobs.
Published: 2026-07-20
Read article →Regex flags and safe testing
What g, i, m, s, and u mean in JavaScript regex — and how to test patterns on pasted text without sending data to a server.
Published: 2026-07-20
Read article →Unix timestamps: seconds vs milliseconds
Why APIs mix 10-digit and 13-digit epoch values, how to tell them apart, and how to convert safely in JavaScript and logs.
Published: 2026-07-20
Read article →Why “local only” matters for developer tools
What browser-local processing means for privacy, compliance, and trust — and when you should still avoid pasting secrets into any website.
Published: 2026-07-20
Read article →Text case styles: camelCase, snake_case, kebab-case
When to use each naming convention, how to convert between them, and pitfalls with acronyms and Unicode.
Published: 2026-07-20
Read article →Subnet math and CIDR explained
How network addresses, prefix lengths, and netmasks relate — IPv4 CIDR basics for firewall rules and cloud VPC design.
Published: 2026-07-20
Read article →Password strength beyond “8 characters”
Entropy, dictionary attacks, and zxcvbn-style scoring — why length and uniqueness beat complex rules on a sticky note.
Published: 2026-07-20
Read article →Converting curl to JavaScript fetch
When to translate curl commands to fetch(), which flags map cleanly, and why parsing locally beats pasting API tokens into online converters.
Published: 2026-07-20
Read article →Generating test JWT tokens locally
How to create HMAC-signed JWTs for API mocks with iat and exp claims — and why signing should stay in your browser or CI, not a random website.
Published: 2026-07-20
Read article →Generating passwords and tokens in the browser
How to create strong random passwords and API tokens with Web Crypto, character classes, ambiguous-character exclusion, and local-only tools—without Math.random or a server.
Published: 2026-07-18
Read article →NanoID vs UUID (size and alphabet)
Compare NanoID and UUID v4 for string length, character set, collision risk, and practical use in URLs, databases, and APIs.
Published: 2026-07-08
Read article →MIME types and file extensions
How type/subtype MIME labels relate to dotted file extensions, why HTTP uses Content-Type instead of filenames, and when the same format has more than one valid label.
Published: 2026-06-26
Read article →Hex encoding: UTF-8 bytes explained
How hexadecimal represents raw bytes, why UTF-8 matters when you encode text as hex, and how hex dumps differ from URL percent-encoding and HTML numeric entities.
Published: 2026-06-26
Read article →ULIDs for sortable IDs
How ULIDs pack a millisecond timestamp and randomness into 26 Crockford base32 characters, why they sort chronologically as plain text, and when to pick them over UUID v4 or NanoID.
Published: 2026-06-26
Read article →UUID versions (and when v4 is enough)
How RFC 4122 UUIDs encode version and variant bits, what versions 1–5 mean in practice, and why random version 4 IDs are the right default for most applications.
Published: 2026-06-26
Read article →HTML entities: what to escape and why
How HTML character references work, which characters must be escaped in text and attributes, and why entity encoding is not the same as URL encoding or full XSS protection.
Published: 2026-06-05
Read article →URL encoding vs form encoding
How percent-encoding works in URLs, when encodeURI differs from encodeURIComponent, and why application/x-www-form-urlencoded treats spaces as plus signs.
Published: 2026-05-27
Read article →CSV to JSON — headers, types, and edge cases
How CSV maps to JSON objects and arrays, why types are ambiguous until you decide, and practical pitfalls like uneven rows, quotes, and BOMs—using browser-only tools on LocalTools.
Published: 2026-05-22
Read article →INI vs Java .properties — when to use which
How INI sections and Java .properties flat keys differ, where each format shows up in real projects, and how to convert between them and JSON locally in your browser.
Published: 2026-05-22
Read article →.env files: syntax, merging, and secrets hygiene
How dotenv-style files are parsed, what happens when keys repeat or files merge, and practical rules for keeping credentials out of the wrong places.
Published: 2026-05-17
Read article →What is JSONPath?
A practical introduction to JSONPath—how to point at nested JSON, filters, and recursive descent—with links to LocalTools’ browser-only evaluator and formatter.
Published: 2026-05-17
Read article →Minifying JSON safely
What JSON minification changes, what it preserves, and when to validate or format again—using browser-only tools on LocalTools.
Published: 2026-05-17
Read article →Generating TypeScript types from sample JSON
How tools infer interfaces from example payloads, what one sample cannot prove, and how to tighten types after generation—all in the browser on LocalTools.
Published: 2026-05-17
Read article →Validating and formatting XML in the browser
What browser-based XML checking really means, how parsing differs from schema validation, and what to expect when you pretty-print or minify—without sending files to a server.
Published: 2026-05-17
Read article →What is TOML?
A plain-language introduction to TOML for config and metadata, how it differs from JSON and YAML, and how to validate it locally in your browser.
Published: 2026-05-17
Read article →What is JSON?
A plain-language introduction to JSON for developers and data wranglers, with a link to LocalTools’ browser-only formatter.
Published: 2026-05-16
Read article →JSON vs YAML for config
When YAML shines for human-edited config, when JSON is the safer default, and how to convert between them locally in your browser.
Published: 2026-05-16
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