Developer guides from the workbench.
Practical, no-fluff guides on JSON, regex, JWTs, DNS, SSL, and email authentication, the things developers debug every day, written alongside the free tools that fix them.
ARC: why forwarded mail fails SPF and DKIM
Forwarding rewrites the path and mailing lists rewrite the message, so authentication that passed at the origin fails at the destination.
Email Header AnalyzerThe bulk sender rules for Gmail and Yahoo, and how to meet them
Sending over 5,000 messages a day to Gmail means authentication, one-click unsubscribe and a spam rate under 0.3 percent.
Email Health (SPF, DKIM, DMARC)Why you cannot put a CNAME at your apex domain
Why a CNAME at your apex domain is illegal, what breaks when you force it, and how ALIAS, ANAME and CNAME flattening solve it.
DNS LookupThe 255 character limit that breaks long DKIM records
Why a 2048 bit DKIM key will not fit one DNS string, how records get split, and the concatenation mistake that silently breaks the key.
DNS LookupHow Let's Encrypt actually issues a certificate
The ACME protocol behind automated certificates: orders, challenges, key authorizations, CAA checks and rate limits.
Alt DCV CheckerHTTP 429: reading rate limit headers and backing off properly
A 429 is an instruction, not an error. How to read Retry-After and the rate limit headers, and why backoff needs jitter to actually work.
API TesterMTA-STS and TLS-RPT: enforcing TLS on inbound mail
STARTTLS can be stripped by anyone in the path. MTA-STS tells sending servers to require TLS for your domain, and TLS-RPT tells you when it fails.
DNS LookupSNI: how one IP address serves hundreds of certificates
TLS must send a certificate before HTTP says which site was wanted. How SNI solves that, and why you sometimes get the wrong certificate.
SSL CheckerWhat MCP is, and why an AI agent needs real network tools
The Model Context Protocol lets an AI assistant call real tools instead of guessing. How it works, and why network diagnostics are the sharp case.
DNS LookupCSV encoding: why Excel mangles your accents and how to fix it
Why Excel shows é instead of é in a UTF-8 CSV, what the byte order mark does, how delimiters change by locale.
JSON ↔ CSV ConverterNano ID vs UUID: choosing an identifier format
How Nano ID and UUID compare on collision risk, length, sortability, and URL friendliness, plus when a shorter ID is safe and when it quietly is not.
UUID & Token GeneratorGreedy vs lazy quantifiers: why your regex matches too much
Why .* swallows the whole line, how lazy quantifiers differ, when a negated character class beats both, and how backtracking causes catastrophic slowdowns.
Regex TesterTime zones and UTC offsets: why storing +05:00 is not enough
The difference between an offset and a time zone, why UTC is not GMT, how DST breaks stored times, and the rules for storing and displaying time correctly.
Timestamp ConverterOAuth 2.0 vs OpenID Connect: authorization is not authentication
Why OAuth 2.0 alone cannot log a user in, what OpenID Connect adds, the difference between an access token and an ID token, and which flow to use today.
JWT DecoderSMTP error codes explained: reading a bounce message
How to read SMTP reply codes and enhanced status codes, what 550 5.7.1 and 421 4.7.0 actually mean, and the difference between a hard and a soft bounce.
Email Health (SPF, DKIM, DMARC)SMTP ports explained: 25, 465, 587, and which one you should use
What each SMTP port is for, the difference between implicit and explicit TLS, why port 25 is blocked on most networks.
MX LookupWebhooks vs polling: choosing how services tell each other things
The real tradeoffs between webhooks and polling, why webhooks need retries and idempotency, when polling is the better engineering decision.
Webhook InspectorCAA records explained: telling CAs who may issue for your domain
What a CAA record does, the exact syntax of issue, issuewild, and iodef tags, how CAs check the tree.
DNS LookupDNSSEC explained: what it signs, what it does not, and how to enable it
How DNSSEC signs DNS answers, what DS, DNSKEY, RRSIG, and NSEC records do, what it does not protect, and the one mistake that takes your domain offline.
DNS LookupMutual TLS explained: when both sides present a certificate
How mTLS differs from ordinary TLS, what the client certificate actually proves, how to issue and verify one.
SSL CheckerServer sent events vs WebSockets: which one do you actually need
How server sent events compare to WebSockets on direction, reconnection, proxies, and cost, plus the event stream format and when polling still wins.
API TesterOKLCH and modern CSS color: why HSL lies about lightness
Why HSL colors at the same lightness look wildly different, what OKLCH fixes, how the three channels work.
Color Converter & Contrast CheckerSelf signed certificates: when they are fine and when they are not
What a self signed certificate is, why browsers reject it, how to generate one properly with SANs.
CSR GeneratorTLS 1.2 vs TLS 1.3: what changed and what you should disable
How TLS 1.3 cut the handshake to one round trip, removed every legacy cipher, what 0-RTT costs you, and which protocol versions to turn off today.
SSL CheckerWildcard vs SAN certificates: which one should you buy
What a wildcard certificate covers and what it does not, how SAN certificates differ, why one wildcard does not cover sub subdomains.
SSL & CSR DecoderContent Security Policy explained: what CSP blocks and how to write one
What a Content Security Policy actually blocks, every directive that matters, why unsafe-inline defeats the point.
HTTP Header CheckerCookie flags explained: SameSite, Secure, HttpOnly, and Domain
What every cookie attribute does, the difference between SameSite Lax, Strict, and None, why Domain widens scope more than you think.
HTTP Header CheckerPing and traceroute: reading what they actually tell you
How ping and traceroute work, why middle hops showing high latency or asterisks is usually normal, what MTR adds.
IP Address LookupWhat is a reverse proxy, and why is one in front of nearly every app
How a reverse proxy differs from a forward proxy, what it handles that your app should not, the headers it must forward, and a working nginx configuration.
Nginx Config GeneratorCan you use comments in JSON? No, and here is what to do
Why JSON has no comments, what error you get, and the real options: JSONC, JSON5, dummy keys, or a different format entirely.
JSON Formatter & ValidatorHow to flush your DNS cache on any system
The exact commands to clear the DNS cache on macOS, Windows, and Linux, plus the browser's hidden cache, when flushing actually helps.
DNS Propagation CheckerHTTP/1.1 vs HTTP/2 vs HTTP/3: what actually changed
What each HTTP version changed and why: head of line blocking, multiplexing, header compression, and why HTTP/3 abandoned TCP for QUIC.
HTTP Header CheckerSymmetric vs asymmetric encryption, explained properly
How symmetric and asymmetric encryption differ, why real systems always use both together, and where AES, RSA, and elliptic curves fit.
Encrypt / Decrypt TextWebSockets vs HTTP: when a request is not enough
How WebSockets work under the hood, the upgrade handshake, when they beat polling and SSE, and the operational costs of holding a connection open.
API TesterCache-Control explained: no-cache, no-store, max-age
How HTTP caching actually works: what each Cache-Control directive does, why no-cache does not mean what it sounds like, ETags and revalidation.
HTTP Header Checkercurl cheat sheet: the commands you actually need
A practical curl reference: GET and POST requests, sending JSON, auth headers, following redirects, saving files, inspecting TLS.
API TesterREST vs GraphQL: an honest comparison
How REST and GraphQL actually differ in practice: overfetching, N+1 queries, caching, error handling, and versioning.
API TesterISO 8601 explained: the only date format worth using
How ISO 8601 dates work: the syntax, what the Z and offsets mean, why the format sorts correctly as text.
Timestamp ConverterWhat is localhost? 127.0.0.1 and 0.0.0.0 explained
What localhost and 127.0.0.1 really are, why 0.0.0.0 is not an address you visit, why a server on 0.0.0.0 is reachable from other devices.
IPv4 Subnet CalculatorCommon network ports: the numbers worth memorizing
What ports are, how well known, registered, and ephemeral ranges work, and a reference table of the port numbers you meet in real work.
IP Address LookupWhere to store JWTs: localStorage vs cookies
The real tradeoff between localStorage and httpOnly cookies for JWT storage: XSS vs CSRF, what each attack can actually do.
JWT DecoderXML vs JSON: differences, and when XML still wins
A practical comparison of XML and JSON: syntax, data model, schemas, namespaces, and performance.
XML FormatterMD5 vs SHA-1 vs SHA-256: which hash should you use?
Why MD5 and SHA-1 are broken for security, where they are still fine, and why SHA-256 is the default.
Hash GeneratorRegex cheat sheet: the patterns you actually use
A practical regular expression reference: character classes, quantifiers, anchors, groups, and flags, plus ready to use patterns for emails, URLs, dates.
Regex TesterHow to check how strong a password really is
What password strength actually measures, why length beats symbol checklists, how crack-time estimates work.
Password Strength AnalyzerConvert CSV to JSON: headers to keys, rows to objects
How a CSV file maps to a JSON array of objects, what happens to types along the way, and the quoting, empty cell.
JSON ↔ CSV ConverterHEX, RGB, and HSL: how to convert colors between formats and when to use each
What HEX, RGB, and HSL actually represent, how conversion between them works, how alpha fits in.
Color Converter & Contrast CheckerHow to convert text between cases: UPPERCASE, camelCase, snake_case, and the rest
How to convert text between UPPERCASE, lowercase, Title Case, camelCase, snake_case, and kebab-case, plus the gotchas with acronyms, numbers.
Case Converter & SlugifyConvert a Unix timestamp to a date (and back) without the 1970 bug
How to turn a Unix timestamp into a readable date and a date back into a timestamp, spot seconds versus milliseconds, and handle timezones correctly.
Timestamp ConverterHow to generate a SHA-256 hash of any text
How to hash a string with SHA-256, SHA-1, or SHA-512, what a digest actually is, where hashes are useful.
Hash GeneratorHow to generate UUIDs online, one at a time or in bulk
What a UUID is, how the version 4 format works, why collisions are not a practical worry, and how to generate one UUID or hundreds at once in your browser.
UUID & Token GeneratorParse a URL into its parts: scheme, host, path, query, and fragment
How to break any URL into scheme, host, port, path, query, and fragment, read query string parameters correctly, and avoid the gotchas that skew results.
URL Encoder & ParserSlugify a title: how to turn any string into a clean URL slug
What a URL slug is and how to make one: lowercase, hyphens for spaces, strip punctuation, transliterate accents.
Case Converter & SlugifyURL-safe Base64 (base64url): what it is and how to encode and decode it
What base64url is, how it differs from standard Base64, why + / and = break URLs, and how to convert and decode it.
Base64 Encode / DecodeGET vs POST vs PUT vs PATCH: HTTP methods explained
What each HTTP method actually means, which ones are safe and idempotent, when to use PUT versus PATCH.
API TesterHTTP vs HTTPS: what the S actually changes
The real differences between HTTP and HTTPS: what TLS encrypts and what it does not, ports 80 and 443, certificates, SEO impact.
SSL CheckerPublic vs private IP addresses: ranges, NAT, and how to tell which is which
The difference between public and private IP addresses, the exact private ranges to memorize, how NAT connects the two.
IP Address LookupRegex for email validation: the pattern that actually works
A practical email regex for JavaScript, Python, and HTML, why the fully RFC-compliant pattern is a trap.
Regex TesterSQL joins explained: INNER, LEFT, RIGHT, and FULL with examples
Every SQL join type explained with the same two small tables: INNER, LEFT, RIGHT, FULL OUTER, CROSS, and self joins.
SQL FormatterTCP vs UDP: differences, ports, and when each one wins
How TCP and UDP actually differ, what reliability and ordering cost, which protocols and ports use each, and why DNS, gaming.
DNS LookupHow to check MX records, and what they actually mean
What MX records do, how to read priorities, the common reasons mail fails to deliver, and how to check a domain's mail servers in seconds.
MX LookupConvert SSL certificate formats: PEM, DER, PKCS#12, and PKCS#7
What PEM, DER, PKCS#7, and PKCS#12 actually are, which servers expect which, and how to convert between them without mangling the key.
SSL ConverterDoes my private key match my SSL certificate? How to check
Why a key and certificate must match, the modulus check that proves it, what the mismatch error looks like, and how to verify the pair safely.
Key MatcherEmbedding images as Base64 data URIs: when it helps and when it hurts
How data URIs inline an image directly into HTML or CSS, the real trade-offs in size and caching, and when embedding beats a normal image request.
Image to Base64Certificate Transparency logs: find every certificate issued for your domain
What CT logs are, why every public certificate is recorded in them, and how to use them to catch unexpected or unauthorized certificates for your domain.
CT Log LookupA secure nginx SSL config, explained directive by directive
The TLS directives that actually matter in an nginx server block: protocols, ciphers, HSTS, OCSP stapling, and the redirect, with what each one does.
Nginx Config GeneratorDomain Control Validation: proving you own a domain for SSL
The three ways a certificate authority checks you control a domain before issuing a cert: HTTP, DNS, and email, plus when to use the DNS alternative.
Alt DCV CheckerWhich CA signed this certificate? Verifying the issuer chain
How certificate signing works, why the issuer and the CA must match cryptographically, and how to confirm a CA actually signed a given certificate.
CA MatcherOCSP and certificate revocation: how browsers check a cert is still valid
Why certificates need a revocation mechanism, how OCSP and CRLs work, what OCSP stapling fixes, and how to check a certificate's revocation status.
OCSP CheckerRSA key formats: PKCS#1 vs PKCS#8 vs SPKI
What the different RSA key encodings mean, how to tell them apart from their PEM headers, which tools expect which, and how to convert safely.
RSA Key ConverterWhat happens when you type a URL and press enter
The full journey from a typed address to a rendered page: DNS, TCP, TLS, the HTTP request, and the response.
DNS LookupHow to decode an SSL certificate or CSR and read its fields
What is encoded inside a PEM certificate or CSR, the fields that matter most, and how to decode and inspect them without uploading anything.
SSL & CSR DecoderERR_SSL_VERSION_OR_CIPHER_MISMATCH: what it means and how to fix it
Chrome throws ERR_SSL_VERSION_OR_CIPHER_MISMATCH when the browser and server share no common TLS version or cipher. The usual causes and the fixes.
SSL CheckerIPv4 vs IPv6: what changed and why it matters
Why the internet ran out of IPv4 addresses, how IPv6 fixes it, what the addresses actually look like, and what you need to know as a developer.
IP Address LookupHow to monitor SSL certificate expiry across many domains
Why expired certificates still cause outages, what to track beyond the expiry date, and how to check many hosts at once before one lapses.
Bulk SSL CheckerWe checked SPF and DMARC on 21 well-known SaaS domains: here's what we found
A reproducible snapshot of the email authentication posture of 21 well-known SaaS companies.
DMARC Record GeneratorBIMI: how to get your logo to show next to your emails
What BIMI is, why it requires DMARC enforcement first, what a VMC certificate adds, and how to publish and check a BIMI record.
BIMI Record CheckerDMARC p=reject is bouncing legitimate email: how to find and fix the gap
When you move DMARC to p=reject, real mail can start bouncing because a sending source was never aligned.
DMARC Record GeneratorAn email deliverability checklist: why your mail lands in spam
The DNS and authentication records that decide whether your email reaches the inbox, in the order to check them, from SPF and DKIM to reverse DNS.
Email Health (SPF, DKIM, DMARC)The TLS handshake explained, step by step
How a browser and server agree on encryption before sending any data: certificates, key exchange, cipher suites, and what TLS 1.3 made faster.
SSL CheckerDNS propagation explained: why your change isn't live everywhere yet
Why a DNS change shows up in some places before others, how TTLs control the delay, and how to read a propagation checker when resolvers disagree.
DNS Propagation CheckerHow text diff works: line, word, and character comparisons
What a diff algorithm actually computes, the difference between line and word diffs, how to read a unified diff, and when each view is most useful.
Text Diff CheckerHow VPN and proxy detection works (and why you got flagged)
What a VPN detector actually checks: ASN and datacenter ranges, known provider lists, protocol probes, and reputation signals.
VPN & Proxy DetectorSPF PermError: too many DNS lookups, and how to get back under 10
SPF allows a maximum of 10 DNS lookups. Cross it and your record returns PermError and stops authenticating mail.
SPF Record GeneratorWhy is my IP blacklisted, and how to get it removed
What DNS blacklists are, the common reasons an IP lands on one, how to check which lists flag you, and the right way to request delisting.
Blacklist CheckWireGuard vs OpenVPN: what goes in a client config file
How the two main VPN protocols differ, what each field in a client config means, and how to generate a working configuration without guesswork.
VPN Config GeneratorNET::ERR_CERT_AUTHORITY_INVALID: why the browser does not trust your certificate
Chrome shows NET::ERR_CERT_AUTHORITY_INVALID when it cannot build a trusted path to a root CA.
SSL CheckerJSON vs TOML: choosing a config format, and converting between them
The strengths and weaknesses of JSON and TOML for configuration, why TOML exists, and how to convert between the two without losing structure.
JSON ↔ TOML ConverterWhat is lorem ipsum, and why placeholder text is still Latin
Where lorem ipsum comes from, why designers use scrambled Latin instead of real copy, and when placeholder text helps a layout and when it misleads.
Lorem Ipsum GeneratorWHOIS and domain lookups: what the records tell you
What a WHOIS lookup reveals about a domain, how registration and expiry data works, why privacy protection hides owners, and how to read the results.
Domain Registration LookupDKIM signature did not verify: the causes, in order of likelihood
A DKIM signature fails for a handful of concrete reasons: a missing or wrong public key, body changes in transit, the wrong selector.
DKIM Record GeneratorHTTP headers explained: the metadata behind every request
What request and response headers do, the ones that matter most for caching, security, and content type.
HTTP Header CheckerWord count, reading time, and readability: what text statistics tell you
How word and character counts, reading time, and readability scores are calculated, what each is good for, and where the numbers mislead.
Text Statistics & Word Counter301 vs 302 redirects: which to use, and why SEO cares
The difference between a 301 permanent and 302 temporary redirect, how each affects SEO and caching, and when 307 and 308 are the right choice instead.
HTTP Status Codestoolhq vs FreeFormatter: formatting XML and more in the browser
FreeFormatter is a broad, long running set of formatters and validators. toolhq does the common XML and JSON jobs entirely in your browser.
XML FormatterWhat's inside a CSR, byte by byte
A certificate signing request is a small ASN.1 structure: a subject, a public key, optional attributes, and a self-signature.
CSR GeneratorA record vs CNAME: when to use each
The difference between an A record and a CNAME, why you cannot put a CNAME at the domain root, and how to choose the right one for each hostname.
DNS Lookuptoolhq vs regex101: quick regex testing vs a full debugger
regex101 is a best in class regex debugger with explanations and multiple flavors. toolhq is for fast, distraction free testing.
Regex TesterAES-256-CBC vs AES-256-GCM: which mode, and why
The difference between AES in CBC and GCM modes, why GCM's built-in authentication matters, and which to choose for new encryption work.
Encrypt / Decrypt TextReverse DNS and PTR records explained
Reverse DNS maps an IP address back to a hostname using PTR records. Learn the in-addr.arpa zone, why mail servers check it, and how FCrDNS works.
Reverse DNS (PTR Lookup)Fixing SSL certificate chain errors: valid in the browser, broken everywhere else
Why a site can look fine in Chrome while curl fails with unable to get local issuer certificate: missing intermediates, AIA fetching.
SSL CheckerHow to read email headers: tracing a message hop by hop
Where to find raw headers in Gmail, Outlook, and Apple Mail, how to read the Received chain from the bottom up.
Email Header AnalyzerSPF, DKIM, and DMARC explained: what each one actually verifies
What SPF, DKIM, and DMARC each prove, why no single one stops spoofing on its own, the record mistakes that break delivery, and a minimal correct setup.
DMARC Record Generatortoolhq vs jwt.io: decoding tokens without sending them anywhere
How toolhq's JWT decoder compares to jwt.io. Both decode in the browser, and one rule matters most: never paste a production token anywhere untrusted.
JWT DecoderUnderstanding DMARC aggregate reports: what the XML is telling you
Why DMARC rua reports arrive as zipped XML, how to read the records inside, what alignment actually means.
DMARC Report ViewerHTML entities: when and how to encode them
Which characters must be escaped in HTML, named versus numeric entities, how encoding prevents broken markup and a class of XSS, and when you can skip it.
HTML Entity Encoder / DecoderCommon MIME types every developer should know
A clear reference to MIME types: what they are, how the Content-Type header works, the charset parameter.
MIME Type Lookuptoolhq vs IT Tools: two browser-first toolboxes compared
IT Tools is an excellent open source, self hostable toolbox. toolhq is a polished hosted set.
UUID & Token GeneratorHow to format SQL queries for readability
Why consistent SQL formatting speeds up review and debugging, the conventions worth adopting, and a before and after example that changes only whitespace.
SQL FormatterEncrypting text in your browser with AES
What AES encryption actually protects, why your passphrase carries the security, and how client side encryption keeps plaintext off every server you touch.
Encrypt / Decrypt TextUnix timestamps and epoch time explained: seconds, milliseconds, and the 2038 problem
What a Unix timestamp actually counts, why some are ten digits and some are thirteen, how time zones fit in.
Timestamp ConverterCIDR notation and subnetting explained: what /24 actually means
How to read CIDR notation, work out how many addresses a subnet holds, find the network and broadcast addresses.
IPv4 Subnet Calculatortoolhq vs CyberChef: when you want simple over a full workbench
CyberChef is a powerful client side workbench for chained operations. toolhq is for the quick single task. Here is when each one is the right call.
Base64 Encode / DecodeHow to verify webhook signatures with HMAC
Webhook endpoints are public, so anyone can POST to them. Learn how HMAC signatures prove a payload came from the real provider and how to verify them.
HMAC GeneratorCSS easing and cubic-bezier curves, made intuitive
What an easing function is, what the built-in keywords actually do, and how the four numbers in cubic-bezier map to a curve.
Cubic Bezier GeneratorUnderstanding chmod and Unix file permissions: what 755 and 644 actually mean
How Unix permissions are structured, how to read and write the octal numbers behind chmod, and the safe defaults for files, scripts, directories.
Chmod CalculatorConverting between binary, hex, and decimal
Understand number bases the practical way: how binary, hex, and decimal relate, why hex maps cleanly onto bytes, and how to convert by hand reliably.
Number Base ConverterHow to format JSON without uploading it anywhere
Most online JSON formatters upload what you paste. How to format and validate locally, and how to verify that for yourself in the network tab.
JSON Formatter & ValidatorHow TOTP authenticator codes work: the math behind the 6 digits
Why the codes in Google Authenticator and Authy change every 30 seconds, how the server verifies them offline.
TOTP Code Generatortoolhq vs CodeBeautify: a privacy-first take on online dev tools
How toolhq and CodeBeautify compare for everyday JSON work, where each one fits, and why a browser only formatter changes how your data is handled.
JSON Formatter & ValidatorURL encoding explained: why spaces become %20 and when you need it
What percent-encoding is, which characters are reserved, the difference between encodeURI and encodeURIComponent.
URL Encoder & ParserCSS gradients explained: linear, radial, and conic
How linear, radial and conic gradients work in CSS: angles, color stops, hard stops for stripes, and layering several in one background.
CSS Gradient GeneratorConvert YAML to JSON and back: the rules that trip people up
YAML and JSON map onto each other, mostly. The gotchas: indentation, types, the Norway problem, anchors and multi-document files.
YAML ↔ JSON ConverterHow to debug webhooks: see what Stripe, GitHub, and others actually send
Webhook integrations fail silently because you cannot see the request. How to capture and inspect real payloads before writing your handler.
Webhook InspectorCORS errors explained: why your API request works in curl but fails in the browser
The request works in curl and Postman but the browser says CORS error. What CORS actually is, why it exists, and how to fix it on the server.
API TesterHow to read an SSL certificate: subject, SAN, chain, and expiry
What the fields in a TLS certificate mean, how the chain of trust works, why the SAN matters more than the common name.
SSL CheckerWhen to use SHA-256 vs HMAC vs bcrypt
What a hash, a MAC and a password hash each guarantee, and which one to use for integrity, authentication and storing passwords.
Hash GeneratorWhat is actually inside a JWT, and why you can read it without the secret
JSON Web Tokens look like random strings but they are readable by anyone. What the three parts contain, what the signature does, and what JWTs cannot do.
JWT DecoderHow strong is your password really? Entropy explained
Password strength is about entropy, not symbols. How it is calculated, why length beats complexity, and what crack-time estimates mean.
Password Strength AnalyzerGenerate TypeScript types from JSON: stop hand-writing interfaces
Why turning a real API response into TypeScript interfaces beats writing them by hand, how optional and nullable fields are inferred.
JSON to TypeScriptWhat every HTTP status code actually means
A practical guide to HTTP status codes by class: when to send each common one, the ones people misuse (401 vs 403, 400 vs 422).
HTTP Status CodesHow to safely share logs and API keys in a bug ticket
Pasting logs into a ticket leaks tokens, emails and internal hosts. How to redact them consistently, and what attackers do with what leaks.
Encrypt / Decrypt TextcamelCase, snake_case, kebab-case, PascalCase: which goes where
A practical guide to the naming conventions you meet daily, why each ecosystem settled on its own.
Case Converter & SlugifyReading a user-agent string: a field-by-field guide
User-agent strings look like noise but follow a pattern. How to read browser, engine, OS, and device out of one, and why they are full of legacy lies.
User-Agent ParserJSON to CSV: turn an API response into a spreadsheet
How to convert a JSON array into clean CSV for Excel or Sheets, including the escaping rules and what happens to nested objects and missing fields.
JSON ↔ CSV ConverterHow to fix "Unexpected token" JSON errors
Unexpected token errors mean your JSON breaks one of five rules. Here is how to find the exact character that breaks parsing and fix it fast.
JSON Formatter & ValidatorGenerate QR codes locally in your browser
Most QR generators send your URL to a server and some add tracking redirects. How client-side QR generation works and why it matters for private links.
QR Code GeneratorOpen Graph tags: how to control how your links look when shared
The handful of meta tags that decide the title, description, and image when your page is shared on Slack, X, LinkedIn, and iMessage.
Open Graph Meta GeneratorMarkdown to HTML: a practical reference
The Markdown syntax that converts cleanly to HTML, the parts that vary between flavors, and how to preview the rendered output as you write.
Markdown PreviewerCron expressions explained with 12 real examples
Cron syntax in five minutes: what each field means, 12 copy paste examples from every minute to quarterly, and the day-of-week trap everyone hits.
Cron GeneratorUUID v4 vs v7: which should you use for database keys?
Random UUIDs fragment database indexes, time ordered ones do not. When v4 is fine, when v7 is better, and why auto increment integers still have a place.
UUID & Token GeneratorRegex lookahead and lookbehind, explained simply
Lookarounds let a regex check what comes before or after a match without consuming it. The four types, real examples, and when not to use them.
Regex TesterDNS records explained: A, AAAA, CNAME, MX, TXT, and NS
What each DNS record type does, how to check them, and how to debug the classic problems: propagation delays, wrong CNAMEs, and failing email.
DNS LookupWCAG color contrast: what AA and AAA actually require
The contrast ratios WCAG requires for text, what counts as large text, which elements are exempt, and how to check your colors in seconds.
Color Converter & Contrast CheckerBase64 is not encryption: what it is and when to use it
Base64 hides nothing. What encoding actually does, where Base64 shows up in web development, and the security mistakes it causes.
Base64 Encode / Decode