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116 free tools that run right in your browser — no install, no login. Formatters and converters for everyday dev work, calculators, text and image utilities, plus electronics and mechanical engineering calculators. Works on mobile and desktop.

Dev44

CSS GeneratorsOverview

Gradients, shadows, transforms and more in one place

JSON FormatterDev

Format, minify, and validate JSON instantly. Syntax highlighting, error detection, stats, and one-click copy.

Diff CheckerDev

Compare two texts and highlight differences line by line. Unified and side-by-side views with inline char diff.

Base64 Encoder / DecoderDev

Encode text or files to Base64, or decode Base64 strings. URL-safe mode, drag & drop file upload, Unicode support.

URL Encoder / DecoderDev

Encode or decode URLs and query strings instantly. Supports encodeURIComponent, encodeURI, and full URL breakdown with query parameter parsing.

Password GeneratorDev

Generate strong, secure passwords instantly. Customize length, character sets, exclude ambiguous chars, and generate up to 20 passwords at once.

Regex TesterDev

Test regular expressions with live match highlighting, capture group inspection, and flag toggles. No lag, no server.

Cron GeneratorDev

Build cron expressions visually. Get human-readable descriptions, presets, and preview the next 5 scheduled run times.

Decode JWT tokens instantly. Inspect header, payload, and claims. Check expiry, algorithm, issuer, and more — fully client-side, nothing sent to server.

UUID GeneratorDev

Generate UUIDs instantly — v4 (random), v1 (time-based), v7 (sortable), and NIL. Bulk generate, customize format, and copy or download.

Hash GeneratorDev

Generate MD5, SHA-1, SHA-256, and SHA-512 hashes from any text instantly. All hashing runs locally in your browser.

Code Formatter & MinifierDev

Beautify or minify JavaScript, CSS, HTML, and SQL instantly. Adjustable indentation, auto language detection, copy & download.

CSS GeneratorDev

Visually build CSS gradients and box-shadows with live preview. Adjust colors, angles, offsets, blur, and spread, then copy the CSS instantly.

Unix Timestamp ConverterDev

Convert Unix timestamps to human-readable dates and back, instantly. Supports seconds & milliseconds, local time & UTC. Live current timestamp.

chmod CalculatorDev

Convert Unix file permissions both ways — toggle owner/group/other r/w/x to get octal (755) and symbolic (rwxr-xr-x), including setuid/setgid/sticky. Runs entirely in your browser.

JSON to TypeScriptDev

Paste JSON and instantly generate TypeScript interfaces or types — nested objects, arrays, unions and nullables inferred. Nothing is uploaded; conversion runs in your browser.

.gitignore GeneratorDev

Generate a .gitignore from templates — pick languages, frameworks, OS and editors, then copy or download the combined, duplicate-free file. Searchable.

cURL to Code ConverterDev

Convert a cURL command into JavaScript fetch, axios, Python requests or Node.js code. Parses method, headers, data and auth — entirely in your browser.

Mock Data GeneratorDev

Generate realistic mock / dummy data as JSON, CSV or SQL — define fields, pick a locale (EN/JA), set row count and an optional seed. Runs in your browser.

SQL FormatterDev

Format and beautify SQL — line breaks on major clauses, indentation, keyword case, indent width and comma position. Best-effort, entirely in your browser.

Number Base & BitwiseDev

Cubic Bezier GeneratorDev

Visual CSS cubic-bezier easing editor: drag the control points, preview the animation live, and copy the cubic-bezier() value. Presets included. In your browser.

Clip-Path GeneratorDev

Visual CSS clip-path editor: drag polygon vertices to craft triangles, stars, arrows and speech bubbles, switch to circle/ellipse/inset, preview live and copy the code. In your browser.

Border Radius GeneratorDev

Round all four corners independently, switch px/%/em, and use fancy mode for elliptical blob/squircle corners. Live preview, one-click copy and shareable links. In your browser.

Flexbox GeneratorDev

Set flex-direction, justify-content, align-items, align-content, flex-wrap and gap with one click, watch a real live layout react, and copy the container CSS. In your browser.

CSS Grid GeneratorDev

Set column and row counts, size each track with fr, px, auto or minmax(), tweak column-gap and row-gap, watch a live grid preview and copy the container CSS. In your browser.

Text Shadow GeneratorDev

Tune offset, blur, color and opacity, stack multiple shadow layers for neon, 3D, outline and glow effects, preview on your own text and copy the text-shadow rule. In your browser.

CSS Filter GeneratorDev

Drag sliders for blur, brightness, contrast, grayscale, hue-rotate, invert, saturate and sepia, watch a live image preview and copy the filter property. Presets included. In your browser.

CSS Transform GeneratorDev

Drag sliders for translate, scale, rotate, skew and perspective, watch a live 3D preview and copy the transform property instantly. In your browser.

Glassmorphism GeneratorDev

Design frosted-glass UI with backdrop-filter: tune blur, transparency, saturation, radius, border and shadow over a colorful backdrop, then copy the CSS with the -webkit- prefix. In your browser.

CSS Button GeneratorDev

Tweak padding, font, border-radius, solid or gradient background, border, shadow and hover effect, watch a real live button, then copy the .btn / .btn:hover CSS. In your browser.

Neumorphism GeneratorDev

Design soft-UI cards: set base color, size, radius, shadow distance, blur, intensity and shape — the light and dark shadows are computed automatically. Copy the CSS. In your browser.

CSS Loader GeneratorDev

Pick a ring, dual-ring, dots, bars or pulse spinner, tune size, color, speed and thickness, watch it animate live, then copy pure-CSS with @keyframes. In your browser.

CSS Animation GeneratorDev

Pick a preset effect (fade, slide, bounce, pulse, shake, spin, flip, zoom), tune duration, delay, timing, iteration and direction, replay the preview and copy the @keyframes + animation CSS. In your browser.

CSS Transition GeneratorDev

Add target properties, set duration, timing-function (ease, linear, cubic-bezier) and delay, then hover or click the live demo to watch it run and copy the shorthand transition CSS. In your browser.

CSS Pattern GeneratorDev

Build stripes, diagonal stripes, checkerboard, polka dots, grid and zigzag patterns with pure CSS gradients — no images. Tweak colors, size, thickness and angle, preview live and copy the background CSS. In your browser.

SVG Blob GeneratorDev

Create smooth, organic random blob shapes for hero backgrounds and decorations. Tweak vertices, randomness, size, color and gradient, then copy a complete SVG snippet or a CSS clip-path. Seeded and shareable by URL. In your browser.

CSS Scrollbar GeneratorDev

Set the width, track color, thumb color, hover color and corner radius, scroll a live preview with your real styling, then copy both the webkit scrollbar rules and the standard scrollbar-width / color properties. In your browser.

Design Tokens GeneratorDev

Pick a base hue and style preset to generate a full CSS custom-property theme — colors, shadows, radius, spacing, type scale and easing — HSL-based, ready to paste into games or UIs. In your browser.

Distinct Colors GeneratorDev

Generate N maximally distinguishable colors with OKLCH — equal perceived brightness and colorblind-aware. Great for game blocks and categories, with color-vision simulation. Copy hex, OKLCH or CSS vars. In your browser.

Contrast CheckerDev

Check the contrast ratio between two colors and verify WCAG AA/AAA pass-fail, with colorblind simulation and improvement hints. Great for game and UI readability. In your browser.

Game Shape Set GeneratorDev

Generate a set of N mutually distinguishable silhouettes for puzzle and game pieces as inline SVG or CSS clip-path, with a built-in silhouette test for colorblind-safe color+shape encoding. In your browser.

Game Material / Gem GeneratorDev

Make flat squares and circles look like gems, orbs, glossy tiles or tactile buttons with gradient, highlight and shadow — no images. Copy the CSS or the Canvas-gradient equivalent. In your browser.

Easing & Motion GeneratorDev

Pick a named easing (ease-out, back, elastic, bounce…), feel it on a live moving box, and copy the cubic-bezier plus a ready-to-paste motion-token set (--ease, --dur). In your browser.

Converters4

Timezone ConverterConverters

Convert time between the world's major timezones. Live world clocks, presets, and shareable links.

Unit ConverterConverters

Convert length, weight, temperature, area, volume, speed, time, and data units instantly. 8 categories, 80+ units.

CSV ⇄ JSON ConverterConverters

Convert between CSV and JSON instantly in your browser. Bidirectional, with delimiter options, header detection, and one-click copy or download.

JSON ⇄ YAML ConverterConverters

Convert between JSON and YAML instantly in your browser. Bidirectional, with validation, formatting, and one-click copy or download.

Calculators9

Calculator (BMI · Age · Days)Calculators

Three free calculators in one: BMI with weight category, exact age in years/months/days, and the number of days between two dates.

Percentage & Discount CalculatorCalculators

Find X% of a number, what percent one number is of another, percentage increase/decrease, and sale prices with tax. Instant, no login.

Loan & Mortgage CalculatorCalculators

Calculate monthly loan and mortgage payments instantly. Supports equal-payment and equal-principal methods, with a full amortization schedule.

Bill Split & Tip CalculatorCalculators

Enter the total, tip %, tax, and number of people to get the amount each person pays instantly — with optional rounding. Free, no login.

Compound Interest & Savings CalculatorCalculators

See the future value of your savings with compound interest. Enter principal, monthly contribution, rate, and term for total interest plus a year-by-year chart.

Sales Tax CalculatorCalculators

Add tax to a net price, remove tax from a gross price, or find the tax amount only. Custom rate plus 8% / 10% presets, instant rounding.

Calorie & BMR CalculatorCalculators

Estimate your BMR and TDEE from height, weight, age, gender and activity level using the Mifflin-St Jeor formula. Targets for losing, maintaining, gaining.

Salary Calculator (Hourly ↔ Annual)Calculators

Convert pay between hourly, daily, weekly, monthly, and annual instantly. Set work hours and days, add a deduction rate, and estimate take-home pay. Any currency.

Due Date CalculatorCalculators

Estimate your pregnancy due date from your last period, conception, or transfer date. See current week and trimester. A general guide, not medical advice.

Text5

Markdown PreviewText

Write Markdown and see the rendered output live. Supports GFM tables, task lists, code blocks, and copy-as-HTML.

Word & Character CounterText

Count words, characters, sentences, paragraphs and reading time instantly. Real-time text statistics with keyword density.

Case ConverterText

Convert text between camelCase, snake_case, PascalCase, kebab-case, CONSTANT_CASE, Title Case, UPPERCASE, lowercase and more.

Lorem Ipsum GeneratorText

Generate Lorem Ipsum placeholder text instantly. Choose paragraphs, sentences, or words, wrap in HTML tags, then copy or download.

Online NotepadText

A free notepad that auto-saves in your browser. Word and character count, .txt download, dark mode. Your notes stay on your device — nothing is uploaded.

Image & PDF13

QR Code GeneratorImage & PDF

Generate QR codes from any text or URL instantly. Customize size, colors, margin, and error correction. Download as PNG or SVG.

Color Palette GeneratorImage & PDF

Generate beautiful color palettes from any base color. Complementary, analogous, triadic, and more. Copy HEX, RGB, HSL. Export as CSS or JSON.

Image → Base64Image & PDF

Convert images to Base64 instantly. Drag & drop or paste from clipboard. Copy as Data URL, raw Base64, CSS background-image, or HTML img tag.

Image Compressor & ResizerImage & PDF

Compress and resize images instantly in your browser. Adjust quality, dimensions, and format (JPEG, PNG, WebP). Reduce file size without uploading.

PDF MergeImage & PDF

Combine multiple PDF files into one, right in your browser. Reorder pages by drag, no upload, no login — 100% private and free.

Image Converter (PNG ⇄ JPG ⇄ WebP)Image & PDF

Convert images between PNG, JPG, and WebP instantly in your browser. Batch convert, set quality, and download — no upload, completely private.

PDF SplitImage & PDF

Split a PDF by page ranges or extract individual pages, right in your browser. No upload, no login — 100% private and free.

Image to PDFImage & PDF

Convert JPG, PNG and WebP images into a single PDF. Reorder by drag, choose paper size, margin and orientation. No upload, 100% private.

Image Crop & RotateImage & PDF

Crop, rotate, and flip images in your browser. Drag to select, lock aspect ratio (1:1 / 16:9 / 4:3), rotate 90°, mirror, and export as PNG, JPG, or WebP. No upload.

Compress PDFImage & PDF

Shrink PDF file size in your browser. Re-encodes and downscales in-page images, with High / Medium / Low levels and before/after comparison. No upload, 100% private.

PDF to ImageImage & PDF

Convert each PDF page to a PNG or JPG image in your browser. Choose resolution, download pages individually or all at once. No upload, 100% private.

Favicon GeneratorImage & PDF

Turn any image into favicons — 16/32/48, Apple touch, and 192/512 PNGs plus ICO. Download all at once with a ready-to-paste HTML snippet. No upload.

Image to Text (OCR)Image & PDF

Extract text from images with in-browser OCR. Drag & drop a PNG, JPG, or WebP and get editable text — English and Japanese supported. No upload, 100% private.

Time & Misc3

Pomodoro Timer / StopwatchTime & Misc

Pomodoro timer, countdown timer, and stopwatch in one. 25/5 work-break presets, custom durations, sound alarm, browser notifications, accurate tab-title countdown.

Countdown TimerTime & Misc

Count down to any date and time with live days, hours, minutes, and seconds. Track multiple events and share via URL. Runs entirely in your browser.

Random Picker (Wheel · Dice · Coin)Time & Misc

Pick a winner from a list with a spinning wheel, generate random numbers, roll dice, or flip a coin. Fun animations, all in your browser.

Electronics18

Electronics CalculatorsOverview

All electronics calculators on one page

LED Resistor CalculatorElectronics

Calculate the series resistor for an LED from supply voltage, forward voltage and current — with nearest E24 value and power dissipation. Runs in your browser.

Voltage Divider CalculatorElectronics

Compute the output of a resistor voltage divider (Vout = Vin·R2/(R1+R2)), reverse-solve resistor values, and see current, power and loaded output. In your browser.

Resistor Series & ParallelElectronics

Calculate the total resistance of resistors in series (sum) or parallel (reciprocal), with any number of resistors and a nearest-E-series combination finder. In your browser.

RC / LC Filter CalculatorElectronics

Find RC low/high-pass cutoff (fc = 1/2πRC) and LC resonant frequency (f0 = 1/2π√LC), with time constants and reactance. Solve forward or reverse, in your browser.

555 Timer CalculatorElectronics

Calculate NE555 astable frequency, duty cycle and on/off times, or monostable pulse width, from R and C values. Switch modes, any units, in your browser.

Voltage Drop CalculatorElectronics

Compute wire voltage drop Vd = k·I·ρL/A, the drop %, end-of-run voltage and one-way resistance. Copper or aluminium, AWG or mm², DC / single- / three-phase, with temperature correction.

PCB Trace Width CalculatorElectronics

IPC-2221 trace width from current, temperature rise and copper weight: A=(I/(k·ΔT^0.44))^(1/0.725), width = A / (oz·1.378). External or internal layers.

Op-Amp Gain CalculatorElectronics

Closed-loop voltage gain, gain in dB and output of an ideal op-amp. Non-inverting (1 + Rf/Rg), inverting (−Rf/Rin) and buffer stages. In your browser.

E-Series Preferred Value CalculatorElectronics

Snap any target to the nearest IEC 60063 E-series value (E6–E192) with percent error, neighbours and tolerance. For resistor and capacitor selection. In your browser.

Enter any two of voltage, current, resistance and power and get the other two — V=IR, P=VI and all the wheel formulas, with unit prefixes. In your browser.

Battery Life CalculatorElectronics

Estimate runtime from capacity and load — by current or power: t = capacity / load × efficiency, with energy in Wh and effective capacity. In your browser.

Impedance CalculatorElectronics

Series RLC reactances Xc=1/(2πfC), Xl=2πfL, impedance |Z|=√(R²+(Xl−Xc)²), phase angle and resonant frequency f0. In your browser.

RMS to Peak CalculatorElectronics

Convert RMS, peak, peak-to-peak and average voltage for sine, square and triangle waveforms, with crest factor, dBV and dBu. In your browser.

Decibel (dB) CalculatorElectronics

Convert voltage/power ratios to dB and back (20·log₁₀ / 10·log₁₀), and dBm ↔ watts. In your browser.

ADC Resolution CalculatorElectronics

Quantization step LSB=Vref/2^N, levels, ideal SNR=6.02N+1.76 dB, dynamic range and ENOB from a measured SNR. In your browser.

Power Loss & Heatsink (MOSFET / IGBT)Electronics

MOSFET / IGBT loss to required heatsink θSA, junction temperature and margin, end to end. SI; verified vs TI / Renesas.

Heatsink Fin θSAElectronics

Fin-array thermal resistance θSA from geometry and convection — fin efficiency η_f and overall η_o; paste a required θSA for pass/fail. SI.

Mechanical23

Mechanical CalculatorsOverview

All mechanical engineering calculators on one page

Metal Weight CalculatorMechanical

Weight of round bar, flat bar, hex, tube, pipe and plate from material and dimensions — per piece, total, volume and cross-section. Steel, aluminum, brass, titanium and custom density.

Hardness Conversion CalculatorMechanical

Convert steel hardness between Vickers (HV), Rockwell C/B/A, Brinell (HB), Knoop (HK) and tensile strength (MPa/ksi). Continuous interpolation per ASTM E140 / ISO 18265.

Bolt Torque & Preload CalculatorMechanical

Tightening torque from target preload, or preload and bolt stress from torque, using T=K·F·d. Metric M3–M36, classes 8.8/10.9/12.9, nut factor K.

Beam Deflection CalculatorMechanical

Maximum deflection, bending stress, bending moment and section I for cantilever and simply supported beams under point or uniform loads. Rectangle, round and pipe sections.

CNC Feeds & Speeds CalculatorMechanical

Spindle RPM = Vc×1000/(π×D), feed rate vf = n·fz·z, feed per rev and material removal rate for milling and drilling. Reverse-solve cutting speed from RPM.

Gear Ratio CalculatorMechanical

Total reduction ratio i = Π(z_out/z_in), output speed N_in/i and output torque T_in·i·η for single- or multi-stage gear trains. Efficiency and pitch-circle diameters.

Press-Fit (Interference) CalculatorMechanical

Contact pressure, hub and shaft hoop stress, insertion force F=π·d·L·p·μ and transmissible torque from a diametral interference, using Lamé thick-cylinder theory. Hollow shaft and dissimilar materials.

Tolerance Stack-Up CalculatorMechanical

Add up dimension tolerances to get the worst-case and statistical (RSS) gap. Variable rows with nominal, +/− tolerance and direction; reports nominal, min–max and ±RSS.

Compression Spring CalculatorMechanical

Spring rate k = G·d⁴/(8·D³·Na), load/deflection, Wahl-corrected shear stress and spring index from wire and coil dimensions. Steel, stainless, bronze and brass.

Thermal Expansion CalculatorMechanical

Length change ΔL = α·L0·ΔT, final dimension and strain from a material coefficient of linear expansion. For shrink-fit and clearance sizing. In your browser.

Sheet Metal Bend CalculatorMechanical

Bend allowance, bend deduction and flat blank length with the K-factor method: BA=(π/180)·θ·(R+K·T). For sheet metal fabrication. In your browser.

Section Modulus CalculatorMechanical

Section modulus Z, moment of inertia I, area, radius of gyration and bending stress σ=M/Z for rectangle, round, tube and box sections. In your browser.

Pulley & Belt CalculatorMechanical

Speed ratio, driven rpm, belt speed and open-belt length from two pulley diameters, the drive speed and the centre distance. In your browser.

Hydraulic Cylinder CalculatorMechanical

Push (extend) and pull (retract) force F=P·A, bore and annulus areas, and rod speed from bore, rod diameter, pressure and flow. In your browser.

Power, Torque & RPM CalculatorMechanical

Any two of power, torque and speed give the third via P=2πNT/60, plus mechanical HP and metric PS. In your browser.

Gear Module CalculatorMechanical

Spur-gear dimensions from module m and teeth z: pitch/tip/root diameter, circular pitch, base circle and centre distance. In your browser.

Bolted Joint Design (VDI 2230)Mechanical

Bolted-joint design to VDI 2230: preload F_Mmax / torque M_A, load factor Φ, embedding loss, fatigue and surface pressure. SI / imperial.

Gear Strength (AGMA)Mechanical

Spur-gear root bending and flank contact stress with AGMA 2001-D04 safety factors, showing which mode governs. SI / imperial.

Fatigue Design (Marin / Goodman)Mechanical

Endurance limit via the full Marin chain, Goodman / Gerber / ASME safety factors and an interactive Goodman diagram. SI / imperial.

Shaft Design (ASME / DE-Goodman)Mechanical

Shaft diameter or fatigue safety factor under combined bending + torsion: DE-Goodman / Gerber / ASME-Elliptic / Soderberg plus first-cycle yield. SI / imperial.

Rolling Bearing Life (ISO 281)Mechanical

ISO 281 rating life L10 and hours from C / P, with the X/Y/e equivalent-load table, reliability factor a1 and modified life. SI / imperial.

Key & Keyway (DIN 6885 / ASME B17.1)Mechanical

Parallel / square key sizing by shear and bearing (h/2), with b×h auto-selected from the shaft band (DIN 6885 / ASME B17.1). SI / imperial.