ToolMars directory
All Free Online Tools
Browse 54 free browser-based developer tools, SEO utilities, image converters, and calculators. No signup, no uploads — everything runs in your browser.
- Batch Image ConverterConvert PNG, JPG, WebP, ICO, and SVG in bulk right in your browser. No uploads or account — download files individually or as a ZIP. Free and private.
- Image CompressorCompress JPEG, PNG, and WebP images in your browser. Adjust quality, cap width, and batch download. No uploads — free, fast, and fully private.
- Blog Image PrepperPrep blog images at 1200×675, 800×450, and author avatar sizes. Auto-crop, WebP export, and sub-100 KB targets — free, private, in your browser.
- JSON FormatterFormat, validate, beautify, and minify JSON instantly in your browser. Free online JSON parser with syntax error detection — no upload, no sign-up.
- Slug GeneratorTurn any title into a clean, SEO-friendly URL slug instantly. Free online slug generator — lowercase, hyphenated, ready for blogs and CMS.
- QR Code DesignerCreate free custom QR codes with your brand colors. Paste a URL or text, preview live, and download a high-resolution PNG instantly—no signup.
- Universal QR ReaderScan QR codes from your webcam or upload an image — free, instant, no app download. Read URLs, text, and contact info right in your browser.
- Word & Text CounterCount words, characters, sentences, and paragraphs as you type. Get reading time, change text case, and clean whitespace. Free, instant — no account required.
- Redirect CompilerPaste old and new URLs to generate 301 redirect configs for Nginx, Apache, or Next.js. Detects redirect loops instantly—free, browser-based, no signup.
- SERP Preview ToolPreview how your title and meta description appear in Google search. Measure pixel widths, export Next.js metadata, and copy code instantly—free.
- Robots.txt GeneratorBuild a valid robots.txt file visually, test Allow and Disallow rules, and block AI scrapers. Free, instant generator with syntax validation. No signup needed.
- Schema GeneratorCreate valid JSON-LD structured data for articles, products, FAQs, and apps. Free, instant schema generator with live validation. Copy ready for Next.js pages.
- Image SEO SanitizerRename images into SEO-friendly filenames, generate alt text, strip EXIF metadata, and export HTML. Free, instant tool — all processing happens in your browser.
- Mortgage CalculatorCalculate monthly mortgage payments, total interest, and a full amortization schedule instantly. Free tool with property tax estimates and CSV download.
- Trading P&L CalculatorCalculate average cost basis, net profit, ROI, and capital gains for stocks and crypto. Free instant P&L tool with exchange fees and tax estimates.
- Age CalculatorCalculate your exact age in years, months, days, and hours from any birth date. See total days lived, next birthday countdown, and age on past or future dates. Free tool.
- CGPA & GPA CalculatorFree CGPA calculator: enter courses, credit hours, and grades to get semester GPA and cumulative CGPA instantly. Private, browser-based, no signup.
- Square Footage CalculatorCalculate square footage instantly for rooms, flooring, and gardens. Free sq ft calculator with rectangle, circle, triangle shapes and waste factor.
- Dividend CalculatorCalculate dividend income and yield from shares, dividend per share, and stock price. Free instant estimates for annual, quarterly, and monthly payouts.
- Gravel CalculatorFree gravel calculator: enter length, width, and depth to get cubic yards, tons, and cost estimates instantly. Perfect for driveways and landscaping.
- Cubic Feet CalculatorCalculate cubic feet from length, width, and height. Convert volume to cubic yards, US gallons, liters, and m³ instantly. Free online cubic feet calculator.
- A1C CalculatorConvert A1C (HbA1c) to estimated average glucose (eAG) in mg/dL or mmol/L, or reverse the calculation. Uses the ADA formula. Educational use only — not medical advice.
- Proportion CalculatorSolve a/b = c/d for any missing value using cross-multiplication. Find unknown numerators or denominators and check equivalent ratios. Free proportion calculator.
- Image ResizerResize images to any pixel size — 16×16 favicons, social banners, or custom dimensions. Export PNG, JPEG, WebP, or ICO. Free, batch, no uploads.
- Markdown to PDF & Word ConverterConvert Markdown (.md) to PDF or Word (.docx) with live preview, syntax highlighting, and batch export. Free, private, no uploads — runs entirely in your browser.
- Word to PDF ConverterConvert .docx files to PDF with page size, margins, and orientation controls. Batch convert with live preview — free, private, no uploads or account.
- Markup CalculatorFree markup calculator: find selling price from cost and markup %, or reverse-calculate profit and margin. Instant results for retail and wholesale pricing.
- Board Foot CalculatorCalculate board feet from lumber thickness, width, length, and quantity. Free instant board foot calculator with cubic feet conversion for woodworking.
- Rounding CalculatorRound numbers to decimal places, significant figures, or nearest step instantly. Free rounding calculator for math, science, and everyday estimates.
- Calculator WatchUse a free four-function calculator with a digital watch look. Add, subtract, multiply, divide, and percent — instant results in your browser.
- Variance CalculatorCalculate variance, standard deviation, mean, and sum of squares from any number list. Switch between population (n) and sample (n−1) mode. Free statistics tool.
- Mixed Number CalculatorConvert mixed numbers to improper fractions and back, or add, subtract, multiply, and divide instantly. Free mixed number calculator with decimal results.
- Mean Median Mode CalculatorFind mean, median, mode, range, min, and max from any number list. Paste comma-separated values and get instant statistics. Free online tool for homework and data.
- Steps to Miles CalculatorConvert steps to miles or miles to steps using custom stride length or height-based estimates. Free, instant calculator with km and calorie estimates. No signup.
- Percent Error CalculatorCalculate percent error, absolute error, and relative error instantly. Free calculator for chemistry, physics lab reports, and science homework.
- Semester Grade CalculatorCalculate your semester grade from weighted categories like homework, quizzes, and exams. Free, instant tool with letter grades and weight-sum warnings. No login.
- Advanced Image CropperCrop images to exact dimensions in your browser. Batch process multiple files, set custom crop areas, and download instantly — free, private, no uploads.
- Invoice GeneratorBuild professional invoices with line items, tax, and discounts. Preview live and download PDF instantly — free, private, no sign-up required.
- Gram to Spoon ConverterConvert grams to tsp and tbsp for flour, sugar, butter & 35+ ingredients. Instant answers for 5g, 10g, 25g — free density-based kitchen tool.
- Food Cost CalculatorCalculate recipe cost per serving, food cost percentage, and ideal menu price. Built for restaurants, caterers, and home meal preppers — free and private.
- Fence Post Concrete CalculatorFree fence post concrete calculator: how many bags of Quikrete per post hole. Enter hole size, post type, and bag weight for 40/50/60/80 lb bag counts, cost, and shopping list.
- Tip Out CalculatorFree tip out calculator for restaurants: split tips by percentage tip-out, hours worked, or role points. Instant per-person totals — private, no signup.
- Cups to Grams ConverterFree cups to grams converter: 1/2 cup flour ≈ 63g, 1 cup sugar ≈ 200g, plus 30+ ingredients. Instant US cup chart — no signup.
- Pan Size ConverterConvert cake and baking pan sizes by volume. Compare round, square, and rectangular pans in cups and cubic inches — free baking calculator.
- BMI CalculatorFree BMI calculator for adults. Enter height and weight in metric or imperial units to get BMI, category, and healthy weight range — private, no signup.
- Percentage CalculatorFree percentage calculator: find X% of Y, what percent A is of B, percentage increase/decrease, and reverse percentages — instant math, no signup.
- Tip CalculatorFree tip calculator: add tip %, split the bill among guests, see tip and total per person. Fast restaurant tip math — private, no signup.
- Discount CalculatorFree discount calculator: find sale price from % off, calculate discount amount, or reverse-engineer original price and percent savings — shopping math made easy.
- Compound Interest CalculatorFree compound interest calculator with contributions. Project future value by compounding frequency, APY estimate, and interest earned — private, no signup.
- Loan EMI CalculatorFree EMI calculator for home, car, and personal loans. Get monthly EMI, total interest, and amortization preview — private, no signup.
- Calorie CalculatorFree calorie calculator using Mifflin-St Jeor BMR and activity-based TDEE. See maintenance, loss, and gain calorie targets — private, no signup.
- Password GeneratorFree secure password generator in your browser. Customize length, symbols, and ambiguous characters — crypto-random, never uploaded.
- Sales Tax CalculatorFree sales tax calculator: add tax to a price or reverse out pre-tax amount from a total. Instant tax math — private, no signup.
- Hourly to Salary CalculatorFree hourly to salary converter (and reverse). Customize hours/week and weeks/year to see weekly, biweekly, monthly, and annual pay.