Guides
Practical walkthroughs for the jobs the tools are built for, and straight comparisons of the formats and algorithms people most often have to choose between. Each guide links to the tools that do the work.
How-to guides
21 guidesStep-by-step instructions for a specific task, with a worked example.
- How to Format JSON Turn minified or broken JSON into something readable, and fix it when it will not parse.
- How to Convert CSV to JSON Turn a spreadsheet export into a clean JSON array, with the delimiter and header options that matter.
- How to Remove Duplicate Lines De-duplicate a list while keeping its order, with the case and whitespace options that decide what counts as a duplicate.
- How to Check DNS Records Look up A, MX, TXT and NS records for a domain, and read what they actually tell you.
- How to Decode a JWT Read the header and payload of a JSON Web Token, check its expiry, and understand why decoding is not verifying.
- How to Test a Regular Expression Build and debug a regex against real sample text, read the capture groups, and avoid the patterns that hang.
- How to Check HTTP Redirects Trace a URL through every hop to its destination, and tell a permanent redirect from a temporary one.
- How to Generate a Secure Password Produce a genuinely random password or passphrase, and understand what actually makes one strong.
- How to Convert XML to JSON Turn an XML document or feed into JSON, and handle the attributes and repeated elements that make it lossy.
- How to Hash Text with SHA-256 Produce a SHA-256 digest, compare it against a published checksum, and know when SHA-256 is the wrong tool.
- How to Compare Two Lists Find what two lists share and what only one of them has, without a spreadsheet formula.
- How to Calculate a Subnet Read CIDR notation and work out the network, broadcast and usable host range.
- How to Convert JSON to SQL Turn a JSON array into INSERT statements, and the traps to avoid when you run them.
- How to Convert a Unix Timestamp Turn epoch seconds into a readable date, and avoid the milliseconds and time zone traps.
- How to URL Encode Text Percent-encode a value safely, and know when to encode the component rather than the whole URL.
- How to Fix Broken Characters in Text Diagnose mojibake, question marks and invisible characters, and repair the text.
- How to Make a Markdown Table Build a pipe table, set alignment, and handle the content Markdown tables cannot hold.
- How to Debug an API Request Work through a failing request in order, from the status code to the payload.
- How to Verify a Webhook Signature Reproduce an HMAC signature correctly, and find out why yours does not match.
- How to Write Meta Tags The head tags that actually matter, what to put in them, and the ones to ignore.
- How to Write a robots.txt Control crawling correctly, and understand what the file cannot do.
Comparisons
15 guidesWhat actually differs between two formats or algorithms, and which to pick.
- JSON vs YAML Which to use for configuration and which for data interchange, and the YAML gotchas worth knowing.
- JSON vs XML Why JSON replaced XML for most APIs, and the cases where XML is still the better answer.
- CSV vs TSV Why a tab separator avoids most quoting problems, and when to use each.
- SHA-256 vs MD5 Why MD5 is broken, what that actually means, and where it is still acceptable.
- SHA-256 vs SHA-512 Both are secure. Which to pick depends on hardware and interoperability, not strength.
- Base64 vs Encryption Base64 is an encoding, not a cipher. What it is actually for, and why it protects nothing.
- JSON Validator vs JSON Formatter Both parse your JSON. They differ in what they give you back and which one to reach for.
- UUID v4 vs v7 Random or time-ordered — which identifier version to use, and why it affects your database.
- UTF-8 vs UTF-16 Two encodings of the same character set, and why string lengths disagree between languages.
- Hashing vs Encryption One-way versus two-way, and why using the wrong one is a security bug.
- Bcrypt vs Argon2 Which password hashing function to use now, and whether an existing bcrypt store needs replacing.
- JWT vs Session Cookies Stateless tokens or server-side sessions — and why revocation is the deciding factor.
- CSV vs JSON Flat tables or nested structures — which format suits the data and the reader.
- Minification vs Compression Two different savings that stack — and why compression does most of the work.
- noindex vs robots.txt Blocking a page and removing it from search are different things — and using the wrong one backfires.