JSON Web Token

Website

jwt.io

$ Details

Platforms

-

Categories

#Identity Provider #Identity And Access Management #SSO #Development

DevTools.fit

Website

devtools.fit

$ Details

-

Platforms

Windows Mac OSX iOS Android Linux Unix

Categories

#Developer Tools #Productivity #Open Source #Programming Tools

JSON Web Token features and specs

• Stateless
  Since JWTs are self-contained, they do not require server-side sessions, enabling stateless authentication and reducing server memory usage.
• Scalability
  JWTs can easily be used in distributed systems and microservices architectures due to their stateless nature, facilitating horizontal scaling.
• Decentralized Issuance
  Multiple issuers can create and sign their own tokens, allowing for more decentralized and flexible authentication mechanisms.
• Performance
  JWTs eliminate the need for database lookups during authenticating requests, as the token contains all the necessary information, which can lead to performance improvements.
• Cross-domain and Mobile Compatible
  JWTs are widely supported by different platforms and can easily be used in cross-domain situations and with mobile applications.
• Security
  JWTs can be signed and optionally encrypted, ensuring the authenticity and integrity of the data they carry.

Possible disadvantages of JSON Web Token

• Size
  JWTs tend to be larger than session IDs, which can increase the amount of data transmitted during requests.
• Expiration Handling
  Managing token expiration can be complex. Once a token is issued, it remains valid until it expires or is explicitly revoked.
• No Built-in Revocation
  Unlike sessions, JWTs cannot be easily revoked server-side, making it difficult to immediately invalidate tokens without additional mechanisms.
• Security Risks
  If a JWT is intercepted or compromised, it can be used until it expires. Thus, it should be properly secured and transmitted over HTTPS.
• Token Overhead
  Embedding too much information in the token payload can lead to performance overhead and potential data exposure risks.
• Complexity
  Implementing JWT correctly requires a thorough understanding of security practices and token lifecycle management, which can add complexity to the system.

DevTools.fit features and specs

• Word counter
  Whether you are polishing an essay, drafting a tweet, or writing a meta description, length limits matter. Universities cap admission essays at strict word counts, Twitter/X stops you at 280 characters, and Google truncates meta descriptions around 155–160 characters. This word counter gives you a live count of words, characters (with and without spaces), sentences, and paragraphs as you type or paste, so you never have to guess whether your text fits. Everything is calculated instantly in your browser. Your text is never uploaded, stored, or sent to any server — which makes this tool safe for confidential documents, unpublished manuscripts, and client work.
• Case converter
  Different contexts demand different letter cases. Headlines use Title Case, constants in code are written in UPPER_SNAKE_CASE, JavaScript variables use camelCase, and URLs prefer lowercase. Retyping text by hand to change its case is slow and error-prone — especially for long documents or large batches of variable names. This converter transforms any text between UPPERCASE, lowercase, Title Case, Sentence case, camelCase, PascalCase, snake_case, and kebab-case in one click. It is equally useful for writers fixing a caps-lock accident and for developers renaming identifiers between naming conventions.
• Lorem Ipsum Generator
  Lorem ipsum is the design industry's standard placeholder text, in continuous use since the 1500s when an unknown printer scrambled a passage of Cicero's De Finibus Bonorum et Malorum to make a type specimen book. Designers use it because its letter distribution looks like natural language, letting viewers judge a layout without being distracted by readable content. This generator produces as many paragraphs, sentences, or words of lorem ipsum as you need — perfect for filling mockups, wireframes, CMS templates, and print layouts while the real copy is still being written.
• Text diff checker
  Comparing two versions of a text by eye is unreliable — a changed date, a deleted clause, or a swapped word is easy to miss. Diff tools solve this by aligning two texts and highlighting exactly what was added, removed, or modified. Programmers use diffs every day in code review, but the technique is just as valuable for contracts, articles, translations, and configuration files. This checker compares two blocks of text line by line and highlights insertions in green and deletions in red, so every difference is visible at a glance. Both texts stay in your browser; nothing is uploaded.
• Find and replace
  Find and replace is one of the oldest and most powerful text-editing operations: change a product name across an entire document, fix a recurring typo, or update a date format in hundreds of lines at once. While most editors offer basic replacement, this tool adds case-sensitivity control and regular expression support, bringing editor-grade bulk editing to your browser. With regex mode you can do far more than literal swaps — collapse repeated whitespace, rewrite phone number formats, or wrap matches in quotes using capture groups. The preview updates live so you can verify the result before copying it.
• Duplicate Line Remover
  Merged mailing lists, concatenated log files, combined keyword exports — the result is always the same: duplicates. Removing them by hand is hopeless past a few dozen lines, and spreadsheet dedupe functions require importing, configuring, and re-exporting. This tool deletes duplicate lines from any text in one click, with options to ignore case and trim whitespace when comparing. It preserves the first occurrence and the original order — paste, clean, copy.
• Line sorter
  Alphabetizing a bibliography, ordering a list of dependencies, ranking numbers, or just imposing order on a chaotic to-do dump — sorting lines is one of those micro-tasks that interrupts real work a dozen times a week. Editors bury the feature in menus; spreadsheets are overkill for a 30-line list. This tool sorts lines alphabetically (A→Z or Z→A), numerically, by length, or in random order — one paste, one click. Random order doubles as a fair way to shuffle names for presentations or draws.
• Text cleaner
  Text copied from PDFs, websites, and Word documents arrives polluted: line breaks in mid-sentence, double spaces, tab characters, smart quotes, invisible non-breaking spaces. Pasting it into a CMS, an email, or code brings the mess along — and cleaning by hand means hunting invisible characters one by one. This cleaner strips the junk in one pass: collapse multiple spaces, remove empty lines, fix broken line breaks, normalize quotes, and trim each line. Paste dirty text, copy clean text.
• Morse Code Translator
  Morse code, developed in the 1830s–40s by Samuel Morse and Alfred Vail for the electric telegraph, encodes each letter as a sequence of short and long signals — dots and dashes. It carried the world's long-distance communication for a century, and it survives today in amateur radio, aviation beacons, accessibility devices, and the universal distress call SOS (··· ——— ···). This translator converts text to Morse and Morse back to text instantly. Letters are separated by spaces and words by slashes, following standard conventions.
• EMOJI pickerand search
  Emoji are governed by the Unicode Consortium — each one is a standardized character with a code point, just like the letter A. There are over 3,800 of them, and finding the right one means scrolling through categories or knowing the magic keyword. A searchable picker turns that hunt into two keystrokes. This picker lets you search emoji by name and keyword, browse by category, and copy any emoji with one click — for use in documents, commit messages, social posts, or code comments.
• Text to Speech
  Every modern browser ships a full speech synthesizer — the Web Speech API — with dozens of voices across many languages. Text-to-speech is bigger than convenience: it powers accessibility for low-vision and dyslexic readers, lets writers hear awkward sentences their eyes skip over, and helps language learners check pronunciation. This tool reads any text aloud with your choice of voice, speed, and pitch — no install, no account, processed entirely by your browser and operating system.
• JSON Formatter & Validator
  JSON is the lingua franca of web APIs, configuration files, and data exchange — but servers usually send it minified into a single unreadable line. A JSON formatter (also called a beautifier or pretty-printer) adds indentation and line breaks so the structure becomes obvious: which objects contain which fields, where arrays begin and end, and where that missing comma broke everything. This tool formats, validates, and minifies JSON entirely in your browser. If the input is invalid, you get the exact parser error so you can fix trailing commas, unquoted keys, or mismatched brackets quickly. Because nothing is uploaded, it is safe for API responses containing private data.
• Base64 Encoder / Decoder
  Base64 is an encoding scheme that represents binary data using 64 safe ASCII characters (A–Z, a–z, 0–9, + and /). It exists because many systems — email, JSON, XML, URLs — were designed for text and can corrupt raw binary bytes. Base64 is how images get embedded in CSS as data URIs, how email attachments survive SMTP, and how credentials are packed into HTTP Basic Auth headers. This tool encodes text to Base64 and decodes Base64 back to text instantly. One crucial point: Base64 is not encryption. It is a reversible encoding with no key and no secrecy — anyone can decode it. Never use it to 'protect' passwords or sensitive data.
• URL Encoder / Decoder
  URLs can only contain a limited set of characters. Spaces, accents, ampersands, question marks and non-Latin letters must be converted to percent-encoding (%20, %C3%A9, %26…) before they can travel safely in a query string. Get it wrong and your link breaks, your API call returns errors, or your analytics parameters get mangled. This tool encodes text for safe use in URLs and decodes percent-encoded strings back to readable text. It is indispensable when you are building query strings by hand, debugging webhooks, reading server logs, or untangling a deeply nested redirect URL.
• HTML Entity Encoder / Decoder
  In HTML, characters like <, >, & and quotes have structural meaning — they open tags and delimit attributes. To display them as literal text, they must be converted to entities: &lt;, &gt;, &amp;, &quot;. Forgetting this is why code snippets vanish from blog posts and why unescaped user input opens the door to cross-site scripting (XSS) attacks. This tool converts text to HTML entities and back. Use it to safely embed code examples in web pages, to debug already-escaped strings from templates and CMSs, or to inspect what a string full of &#x27; sequences actually says.
• Hash Generator
  A hash function takes any input and produces a fixed-length fingerprint — change a single byte of the input and the hash changes completely. Hashes are how downloads are verified, how git identifies commits, how systems detect duplicate files, and (with the right algorithms) how passwords are stored. This tool computes MD5, SHA-1, SHA-256 and SHA-512 hashes of any text directly in your browser using the Web Crypto API. It is ideal for verifying file checksums published by software vendors, generating cache keys, or comparing whether two pieces of text are identical without reading them.
• UUID Generator
  A UUID (Universally Unique Identifier) is a 128-bit identifier that can be generated anywhere, by anyone, at any time — with no central authority and no realistic chance of collision. That property makes UUIDs the default choice for database primary keys in distributed systems, request tracing IDs, file names in object storage, and any situation where two machines must mint identifiers independently. This generator produces version 4 UUIDs, which are built from cryptographically random numbers. Generate one or dozens at a time and copy them straight into your database seeds, configuration files, or test fixtures.
• Regex Tester
  Regular expressions are a compact pattern language for matching text — phone numbers, emails, log lines, dates — supported by virtually every programming language and editor. They are also notoriously easy to get wrong: one misplaced quantifier and your pattern matches too much, too little, or nothing at all. This tester lets you write a pattern and see matches highlighted live against your sample text, with support for flags (global, case-insensitive, multiline) and capture groups. Iterating visually is the fastest way to build a correct regex before committing it to code.
• Markdown preview
  Markdown is the plain-text formatting language behind GitHub READMEs, documentation sites, Reddit posts, and most note-taking apps. You write readable symbols — # for headings, ** for bold, - for lists — and they render as clean HTML. The catch: until you render it, it is easy to break a link, nest a list wrong, or forget a blank line before a heading. This live preview renders your Markdown as you type, side by side with the source. Draft a README, check a table, or verify code blocks before you commit — without pushing to GitHub just to see how it looks.
• Color Converter
  The same color can be written many ways: designers hand you #FF6B35, CSS variables use rgb(255, 107, 53), and modern stylesheets increasingly prefer hsl(16, 100%, 60%) because humans can reason about hue, saturation and lightness. Converting between formats by hand requires non-obvious math — this tool does it instantly and shows a live swatch of the color. Paste any HEX, RGB, or HSL value and get all equivalent forms at once, ready to copy into your stylesheet, design tool, or brand guide.
• JWT Decoder
  JSON Web Tokens (JWT) are the standard format for authentication tokens in modern web apps and APIs. A JWT is three Base64Url-encoded parts joined by dots: a header (algorithm and type), a payload (claims like user ID, roles, and expiry), and a signature. When login breaks or an API returns 401, decoding the token is usually the fastest way to see why. This decoder splits a JWT and pretty-prints its header and payload, including human-readable dates for the iat (issued at) and exp (expiry) claims. Decoding happens entirely in your browser — the token is never transmitted — and no secret key is needed because the payload is encoded, not encrypted.
• JSON to TypeScript
  When a TypeScript app consumes an API, every response needs a type — and writing interfaces by hand from a sample response is tedious and error-prone: one mistyped field name and the compiler trusts a lie. Generating types from real JSON eliminates both the typing time and the typos. This tool converts any JSON object or array into TypeScript interfaces, inferring types for nested objects, arrays, optional-looking fields, and primitives. Paste an API response, copy ready-to-use interfaces.
• Cron expression parser
  Cron expressions schedule the automated world: nightly backups, hourly syncs, Monday-morning reports. Five space-separated fields — minute, hour, day of month, month, day of week — encode the schedule, but their syntax (*/15, 1-5, MON-FRI) is famously hard to read back. A misread cron line can mean a backup that silently never runs. This parser translates any cron expression into plain English and shows the next scheduled run times, so you can verify a schedule before deploying it to crontab, GitHub Actions, Kubernetes, or your CI system.
• JSON path finder
  Deeply nested API responses bury the value you need five levels down: data.results[3].user.profile.email. Finding it by eye in a wall of braces is slow; mistyping the path in code costs a debugging round-trip. A path finder shows the structure as a navigable tree and hands you the exact path expression. Paste JSON, click any value in the tree, and copy its precise access path — ready for JavaScript, Python, or your favorite JSON library.
• Unix Timestamp Converter
  Unix time counts the seconds elapsed since January 1, 1970, 00:00:00 UTC — the 'epoch'. It is how databases store dates, how APIs exchange them, and how log files record events, because a single integer is unambiguous, timezone-free, and trivial to compare. The downside: 1750000000 means nothing to a human. This converter translates timestamps to readable dates (in both UTC and your local timezone) and converts dates back to timestamps. It handles both seconds and milliseconds — the most common source of off-by-1000 confusion between systems.
• Roman natural converter
  Roman numerals survive antiquity on clock faces, movie credits, Super Bowl titles, monarch names, and book chapters. The system uses seven letters (I, V, X, L, C, D, M) and a subtractive rule — IV is 4, IX is 9, XC is 90 — that makes both reading and writing them error-prone for anyone who does not practice. This converter translates numbers (1–3999) to Roman numerals and back, validating input so malformed numerals like IIII or VX are flagged rather than silently misread.
• Text to binary converter
  Underneath every character you read is a number, and underneath every number is binary. The text-to-binary conversion makes that visible: each character maps to its Unicode code point, encoded in bits — 'A' is 01000001, 'a' is 01100001. It is the literal answer to 'how do computers store text', which makes this conversion a staple of CS education, encoding puzzles, and geek culture. This tool converts text to binary (8-bit groups) and binary back to text, instantly and locally.
• Password Generator
  The passwords people invent are catastrophically predictable: dictionary words, birthdays, keyboard walks, and the inevitable trailing '123!'. Attackers know every trick and test billions of guesses per second against leaked password databases. The only reliable defense is length and true randomness — which humans are incapable of producing mentally. This generator creates cryptographically random passwords using your browser's secure random source. Choose the length and character sets, and the password never leaves your device — it is generated locally and is never transmitted or stored.
• Slug generator
  A slug is the human-readable part of a URL that identifies a page: in example.com/blog/how-to-learn-python, the bold part is the slug. Good slugs are lowercase, hyphen-separated, free of accents and punctuation, and short enough to read at a glance — qualities search engines explicitly reward and users instinctively trust. This generator converts any title into a clean slug: it lowercases the text, transliterates accented characters (café → cafe), strips punctuation, and joins words with hyphens. Paste a headline, copy a URL-ready slug.
• Random Number Generator
  Picking a giveaway winner, assigning teams, rolling initiative in a tabletop game, sampling rows from a dataset — all of these need numbers free of human bias. People asked to 'pick a random number' gravitate to 7 and 37 and avoid round numbers; real randomness requires an algorithm. This generator produces uniformly distributed random integers in any range you choose, with options for multiple draws and duplicate-free results — ideal for raffles where each entry may win only once.
• Image Resizer
  Image files are the heaviest part of most uploads — a modern phone photo is 4000+ pixels and several megabytes, while a forum avatar needs 256 pixels and a web banner under 200 KB. Resizing usually means installing software or trusting a website that uploads your photos to its servers. This resizer works entirely in your browser using the canvas API: the image is loaded locally, scaled to your target dimensions, and re-exported as PNG or JPEG. Your photos never leave your device — suitable even for ID scans and private pictures.
• Typing Speed Test
  Typing speed is measured in WPM — words per minute, where a 'word' is standardized as five characters. The average typist manages around 40 WPM; competent touch typists reach 60–80; professionals exceed 100. Since a knowledge worker types for hours daily, the gap between 40 and 80 WPM compounds into entire workdays saved per month. This test measures your speed and accuracy on a random text passage in real time. Take it a few times to get a stable baseline, then track your progress as you practice.
• QR Code Generator
  QR codes — invented at Denso Wave in 1994 to track car parts — became the universal bridge between physical and digital: menus, payments, ticketing, Wi-Fi sharing, packaging. A QR code encodes text (most often a URL) in a grid of modules with built-in Reed–Solomon error correction, which is why a scuffed or partially covered code still scans. This generator creates a QR code from any text or URL, entirely in your browser. Download the image and print it on flyers, slides, menus, or business cards.
• Favicon Generator
  The favicon — the tiny icon in browser tabs, bookmarks, and history — is your site's smallest but most persistent branding surface. A missing favicon shows a generic globe and instantly signals 'unfinished site'. Modern favicons are not one file but a small set: classic 16/32-pixel icons, a 180-pixel Apple touch icon, and 192/512-pixel icons for Android and PWA installs. This generator takes one square image and produces the complete favicon set in your browser, along with the HTML link tags to paste into your <head>.
• Screen resolution checker
  'What resolution is my screen?' has a surprisingly layered answer: the physical pixel count, the CSS viewport your browser actually exposes to websites, and the device pixel ratio (DPR) linking the two on high-density 'Retina' displays. Web developers, support technicians, and display shoppers all need these numbers — and they are buried in system settings. This checker displays your screen resolution, current viewport size, device pixel ratio, and color depth live — resize the window and watch the viewport numbers follow.
• Percentage calculator
  Percentages are everywhere — discounts, taxes, tips, interest, statistics, grade curves — yet the three classic questions are easy to mix up: What is 15% of 80? 12 is what percent of 60? What is the change from 50 to 65? Each needs a different formula, and reaching for the right one under time pressure is where mistakes happen. This calculator answers all three forms instantly, plus percentage increase and decrease. Type the numbers, read the result — with the formula shown so you understand what was computed.
• Age Calculator
  How old is someone born on February 29, 1996, today — in years, months, and days? Age arithmetic sounds trivial but is full of traps: months have different lengths, leap years shift day counts, and 'one month later' from January 31 has no obvious answer. Official forms, visa applications, and medical records often want the exact figure. This calculator computes precise age from a birth date: full years, remaining months and days, plus total days lived. It handles leap years and month-length differences correctly.
• BMI Calculator
  Body Mass Index — weight in kilograms divided by height in meters squared — has been the standard population-level screening measure for weight categories since the 1970s. The WHO ranges classify a BMI under 18.5 as underweight, 18.5–24.9 as normal, 25–29.9 as overweight, and 30+ as obese. This calculator computes BMI from metric or imperial units and shows where the result falls on the WHO scale. Remember that BMI is a screening tool, not a diagnosis: it cannot distinguish muscle from fat and should be interpreted alongside other health measures, ideally with a healthcare professional.
• Tip Calculator
  Splitting a dinner bill among five people with a 18% tip should not require a spreadsheet — yet doing it in your head while the waiter waits is a classic small stress. Tipping norms also vary wildly: 15–20% is standard in the United States, while service is typically included in much of Europe and tipping can even be unusual in parts of Asia. This calculator computes the tip, the total, and the per-person share instantly. Adjust the percentage to match the country, the service, and your generosity.
• Aspect ratio calculator
  Resize a 1920×1080 video to fit a 1280-pixel-wide player, crop a photo for a 4:5 Instagram post, or letterbox 21:9 footage onto a 16:9 screen — every one of these is an aspect-ratio problem. Get the math wrong and images stretch, faces distort, and videos grow black bars in the wrong places. This calculator keeps width and height locked to a ratio: enter any three values and it solves the fourth, and it can reduce any resolution to its simplest ratio (1920×1080 → 16:9).
• Online stopwatch
  From timing a 5K interval workout to measuring how long a database migration actually takes, a stopwatch is one of the simplest, most universally useful instruments. The lap function adds the crucial ability to capture split times without stopping the clock — essential for training sessions, presentations, and any repeated process you want to compare round by round. This browser stopwatch starts instantly, records unlimited laps, and runs with centisecond display precision. No app to install, no permissions to grant.
• Countdown timer
  Deadlines focus the mind. A visible countdown turns an abstract 'twenty minutes left' into a concrete, ticking number — which is why countdowns run exams, cooking, presentations, auctions, and product launches. Psychologically, a running timer is one of the simplest known antidotes to procrastination: it converts open-ended time into a bounded challenge. This timer counts down from any duration you set, with a clear display and an alert when time is up. Set it for a pasta pot, a meeting timebox, or a writing sprint.
• Pomodoro Timer
  The Pomodoro Technique, created by Francesco Cirillo in the late 1980s and named after his tomato-shaped kitchen timer, structures work into 25-minute focused sessions separated by 5-minute breaks, with a longer break after every fourth session. The method works because it makes starting easy (anyone can commit to 25 minutes), bans multitasking within a session, and schedules recovery before fatigue accumulates. This timer automates the full cycle — work, short break, long break — so you can keep your attention on the task instead of the clock.
• CSS gradient generator
  Flat colors are easy; gradients give interfaces depth, energy, and that modern feel — hero sections, buttons, cards, and mesh-style backgrounds all lean on them. Writing linear-gradient() by hand means guessing angles and color stops, reloading, and guessing again. This generator gives you a live preview while you pick colors, adjust stop positions, and set the angle — for both linear and radial gradients — then outputs clean CSS ready to paste into your stylesheet.
• CSS box shadow generator
  Shadows are how flat screens fake depth: a subtle box-shadow lifts a card off the page, signals that a button is pressable, and separates a modal from the content behind it. The CSS syntax — offset-x, offset-y, blur, spread, color — is simple, but the difference between elegant and amateurish lives in values you can only judge visually. This generator lets you tune every parameter with sliders against a live preview, including inset shadows and layered multi-shadow setups, then copies production-ready CSS.
• Meta Tag Generator
  Meta tags are how your page introduces itself to the world: the title and description Google shows in results, the image and headline that appear when someone shares your link on social networks. Missing or sloppy tags mean truncated snippets, blank share cards, and clicks lost to better-presented competitors. This generator builds the full set — title, description, canonical, Open Graph for Facebook/LinkedIn, and Twitter Card tags — from a simple form, producing copy-paste-ready HTML for your page's <head>.
• Color Palette Generator
  A user interface rarely fails because one color is ugly — it fails because colors do not work together. Color harmony has rules: complementary colors (opposite on the wheel) create energy, analogous colors (neighbors) create calm, triadic schemes balance vibrancy and order. Designers internalize these rules; generators apply them instantly. This tool generates harmonious five-color palettes — randomly or from a base color you pick — and shows each color's HEX code ready to copy into your design system.

Analysis of JSON Web Token

JSON Web Tokens Suck - Randall Degges (DevNet Create 2018)

More videos:

No DevTools.fit videos yet. You could help us improve this page by suggesting one.

Add video