Guides
Start with the core developer tools below, then dig into blog how-tos. Everything runs locally — cite our privacy pagewhen you need the no-upload promise.
Core tools
- JSON FormatterPretty-print, validate, and minify JSON locally — safe for sensitive payloads.
- JSON DiffStructural diff of two JSON objects in your browser.
- Cron HelperExplain cron expressions and preview the next runs in your timezone.
- Timestamp ConverterUnix epoch ↔ human dates — local, UTC, and ISO.
- JWT DecoderDecode claims, flag alg:none, optional HS256 verify — token stays in this tab.
- Hash GeneratorSHA and MD5 of text or local files via Web Crypto.
- UUID GeneratorBulk UUID v4 and v7 — cryptographically random or time-sortable.
- Base64 Encode / DecodeUTF-8 safe Base64 for text and files — encoding, not encryption.
Reference
- Cron expression cheat sheetFive fields, special characters, common presets — then explain with Cron Helper.
- Private JSON workflowFormat → diff → Base64 → JWT in one chain — bookmark once.
- Private JSON vs cloud formattersWhen in-browser formatting beats pasting secrets into a random site.
- HTTP status codesOne hub for 2xx–5xx meanings — use this instead of one-off status pages.
- Number base converterHex, decimal, binary, and octal in one tool — with an ASCII table nearby.
Popular cron schedules
All featured tools
- JSON FormatterFormat, validate, and minify JSON privately in your browser.
- JSON DiffStructural diff of two JSON objects — not a noisy text diff.
- Timestamp ConverterUnix epoch ↔ human dates, live clock, any timezone basics.
- Cron HelperExplain cron in English and preview the next five runs.
- JWT DecoderDecode JWT claims, spot alg:none, optional local HS256 verify.
- Hash GeneratorSHA-1/256/384/512 and MD5 of text or local files.
- UUID GeneratorGenerate UUID v4 and v7 values in bulk.
- Base64 Encode / DecodeUTF-8 safe Base64 encode/decode for text and local files.
- Word CounterCount words, characters, and reading time privately.
- Password GeneratorGenerate strong random passwords locally.
- XML FormatterPretty-print and validate XML with DOMParser — nothing uploaded.
- XML to JSONConvert XML to a nested JSON tree in your browser.
- JSON Schema ValidatorValidate JSON against a JSON Schema (Draft-07 subset) locally.
- JWT EncoderBuild and sign an HS256 JWT with Web Crypto — for testing.
- RGB ↔ HSL ↔ CMYKConvert colors between RGB, HSL, and CMYK with a live swatch.
- IP / CIDR CalculatorExpand IPv4 CIDR to network, broadcast, and host range.
- Regex TesterTest JavaScript regex with recipes; copy as JS or Python.
Honest alternatives (browser-only)
- JSONLint alternativeFormat and validate JSON locally — plus diff, minify, and CSV export.
- JSONFormatter alternativePretty-print sensitive API payloads without uploading to a remote formatter.
- jwt.io alternativeDecode JWT claims in your tab — optional HS256 verify.
- crontab.guru alternativeExplain cron schedules and preview next runs locally.
- EpochConverter alternativeUnix epoch ↔ dates in any timezone — no upload.
From the blog
July 26, 2026
CORS Explained: Why Your Fetch Request FailedThe request usually succeeds on the server — the browser just refuses to hand the response to your JavaScript. CORS is a browser rule, not a network failure, and the fix is almost always on the server, not your fetch call.July 26, 2026
Number Bases Explained: Binary, Octal, Decimal, HexA number base is just how many digits you get before you carry — decimal carries at 10, binary at 2, hex at 16. Once that clicks, every binary/hex value stops looking like a secret code.July 25, 2026
HTTP Methods: GET vs POST vs PUT vs PATCH vs DELETEGET reads, POST creates, PUT replaces, PATCH updates part of a resource, DELETE removes it. The details that trip people up are safety and idempotency — not the names.July 25, 2026
JSONFormatter & CodeBeautify: What Was ReportedThree independent outlets reported that two widely-used JSON tools stored what you pasted, on a guessable public URL, for years. Here's a summary of that reporting, with sources, and what a no-upload tool changes structurally.July 22, 2026
Cron Every N Minutes: Quick CheatsheetNeed “every N minutes” without guessing step syntax? Here are the classic five-field expressions, what they fire, and how to preview them safely.July 22, 2026
HTTP 401 vs 403 vs 404 Explained401 means “who are you?”, 403 means “I know you, but no,” and 404 means “nothing here (or I will not say).” Mixing them up sends you to the wrong layer of the stack.July 22, 2026
MD5 vs SHA-1 vs SHA-256 vs SHA-512Same input, four digests — different lengths and threat models. Use SHA-256 (or SHA-512) for integrity; treat MD5 and SHA-1 as legacy unless a system forces them.July 22, 2026
Unix Epoch to IST, EST, PST — LocallyAn epoch is a UTC instant. “Epoch to IST” means format that instant in India time — not a different kind of timestamp. Here is how to do it without a time API.July 20, 2026
Minify JSON Without Uploading SecretsPretty-print for humans; minify for transfer. Both should stay local when the payload may contain secrets.July 20, 2026
Private JSON Workflow — Format, Diff, JWTOne formatter is easy to copy. A private format → diff → encode → JWT chain is the workflow worth bookmarking when payloads may contain secrets.July 19, 2026
Binary Translator — Text to Binary and BackNeed to see the bits behind a string? Translate text ↔ binary locally without pasting messages into a cloud bit converter.July 19, 2026
camelCase, snake_case, and kebab-case ConverterAPIs want snake_case, JS wants camelCase, CSS wants kebab-case. Convert identifiers locally without a noisy online renamer.July 19, 2026
Character Counter and Byte Length LocallyDraft tweets, meta descriptions, and SMS-length copy with live counts — not uploaded to our servers for processing, no account.July 19, 2026
HTML Entities Encode and Decode LocallyEscape special characters for safe HTML, or decode entities back to text — all in your tab, not uploaded to our servers for processing.July 19, 2026
JWT vs Base64 — What Is the Difference?Base64 hides bytes as text. A JWT is a signed structure that happens to use Base64URL. Mixing them up causes security mistakes.July 19, 2026
When to Use Lorem Ipsum (and When Not To)Lorem ipsum is for layout, not content strategy. Generate filler locally, then replace it before anything ships.July 19, 2026
Markdown Preview Without Uploading Your DraftWant a live Markdown preview for a README or post? Render it in your tab so unpublished drafts are not uploaded to our servers for processing.July 19, 2026
Remove Duplicate Lines and Sort Text ListsDuplicate lines in a list? Remove them and sort locally so emails and IDs never hit a cloud “unique lines” tool.July 18, 2026
chmod 755 and rwx Permissions Explained755 means rwxr-xr-x. Learn the octal bits, common modes, and calculate chmod values without memorizing every combo.July 18, 2026
Hex to RGB and HSL: Copy CSS Color ValuesTurnJuly 18, 2026
404 vs 500: HTTP Status Codes404 means the resource was not found. 500 means the server failed. Here is how to tell them apart — and what to check next.July 18, 2026
Number Base Converter: Hex, Decimal, and BinarySwitch hex ↔ decimal ↔ binary without a spreadsheet. Watch signedness and bit width so 0xFF is not a surprise.July 17, 2026
Cron: Crontab vs GitHub Actions, Vercel, and KubernetesThe same “cron” string can mean different things on Linux, Actions, Vercel, and K8s. Know the dialect before you deploy.July 17, 2026
Format HTML and Minify CSS LocallyBeautify HTML for debugging, minify CSS for size checks — both can stay on-device with TryDevSnip tools.July 17, 2026
Pretty-Print SQL in the BrowserGot a one-line SQL monster from a log? Pretty-print it in your browser without pasting the query into a cloud formatter.July 16, 2026
Base64 Encode/Decode: UTF-8 PitfallsBase64 is not encryption. It is a transport encoding — and UTF-8 mistakes are why “decode” suddenly looks like mojibake.July 16, 2026
Cron for Hourly & Midnight Jobs“Every 5 minutes” is common. “Every hour” and “every day at midnight” are the next two expressions people look up when wiring backups and reports.July 16, 2026
Cron Timezones: UTC vs Local Next RunsThe expression can be perfect and still fire at the “wrong” hour. Cron uses the scheduler’s timezone, not whatever your laptop shows.July 16, 2026
Cron for Weekdays at 9 AM Explained“Weekdays at 9am” is one of the most copied cron patterns — and one of the easiest to get wrong on day-of-week numbering or timezone.July 16, 2026
Convert a Date to a Unix TimestampEpoch → date is common. Date → epoch is the inverse: pick the timezone of the wall clock you typed, then choose seconds or milliseconds.July 16, 2026
Fix Unexpected Token JSON Errors“Unexpected token” usually means the parser hit something that is not valid JSON — a comma, a quote, or an HTML login page pretending to be data.July 16, 2026
JSON Diff — Structural, No UploadText diffs scream about commas and key order. Structural diffs answer the question you meant: what actually changed in the data?July 16, 2026
Diff Text Without Uploading to a Cloud ToolNeed a quick text diff for configs or copy? Compare locally so drafts and credentials never hit a pastebin-style diff site.July 16, 2026
Epoch to UTC — Unix Timestamp to DateEpoch to UTC is formatting: the Unix timestamp is already UTC-based. The usual bug is seconds vs milliseconds, or showing UTC as if it were local.July 16, 2026
URL Encode and Decode Query StringsSpaces become %20 (or +), and & breaks params. URL-encode values locally before you ship a broken query string.July 15, 2026
CSV to JSON and JSON to CSV LocallyNeed CSV ↔ JSON for a quick import? Convert both ways locally so customer rows never hit a cloud spreadsheet converter.July 15, 2026
Format JSON Without Pasting It to the CloudNeed pretty JSON without handing API keys to a random website? Format it in your browser — nothing uploads.July 15, 2026
Pretty-Print JSON Without Uploading SecretsPretty-printing is harmless until your JSON includes secrets. Keep formatting on your device.July 15, 2026
Regex Tester Recipes for JavaScript and PythonRegex is easier when you can iterate live. Test JS and Python-style patterns locally with clear matches and groups.July 15, 2026
Convert YAML to JSON Without Pasting SecretsYAML configs often hold secrets. Convert them to JSON in the browser so indentation fixes never require an upload.July 14, 2026
Generate a Strong Password Without Uploading ItStrong passwords need entropy, not a witty phrase. Generate them locally so the secret never hits someone else’s server.July 14, 2026
UUID v4 vs v7: Which to Use and How to Bulk GenerateRandom v4 UUIDs are fine for most IDs. Time-ordered v7 helps indexes. Generate either in bulk without a server round-trip.July 14, 2026
Don't Paste JSON Into Random SitesA “free JSON formatter” that uploads your paste is a silent data leak. Here is what usually hides in JSON — and how to format it without leaving your machine.July 14, 2026
Word Count and Reading Time ExplainedWord count is simple until you hit CJK, hyphenation, and “200 wpm” reading-time myths. Here is what the numbers actually mean.July 13, 2026
JWT Decode: alg none Risks and Local HS256 ChecksNeed to read a JWT header and payload without shipping the token to a third-party decoder? Do it locally — and never trust alg none.July 13, 2026
SHA-256 Checksums for Text and Files in the BrowserNeed a SHA-256 checksum for a string or file? Hash it in your tab. Same crypto, zero upload.July 12, 2026
Unix Timestamp: Seconds vs MillisecondsA 13-digit “timestamp” is not the same unit as a 10-digit one. Mixing them up shifts dates by centuries — or makes every API look broken.July 10, 2026
Crontab Every 5 Minutes (*/5 * * * *)“Every 5 minutes” looks trivial until you hit five-field vs six-field cron, time zones, and jobs that overlap. Here is the expression — and what it actually means.