Free · Browser-Based · No Signup · Instant Results
Free Online Developer Tools That Open Fast and Get Out of Your Way
Toolkit.Fun is a lightweight collection of browser-based tools for developers, operators, and technical teams. The current batch already covers JSON, Base64, URL encoding, timestamps, JWT inspection, regex testing, text diff, and writing helpers.
100Live Tools
100%Browser-based
0Signup Required
💻 Available Developer Tools
Built for common daily tasks: inspect data, clean payloads, convert formats, and reduce friction during debugging.
Featured
JSON Formatter
Format, validate, minify, and inspect JSON locally in the browser.
Base64 Encoder
Encode or decode Base64 locally for payload, token, and API debugging.
URL Encoder
Encode unsafe URL characters and decode percent-encoded strings.
Unix Timestamp Converter
Convert Unix time to readable dates and back with UTC/local awareness.
JWT Decoder
Decode JWT headers and payloads with readable claim timestamps.
Regex Tester
Test patterns, review matches, and try replacements quickly.
HTML Escape
Escape or unescape HTML entities for templates, docs, and snippets.
JSON String Escape
Convert plain text into JSON-safe strings and back.
Text Diff Checker
Compare two text blocks with a side-by-side line diff summary.
Word Counter
Count words, characters, lines, paragraphs, and reading time instantly.
URL Parser
Parse full URLs, inspect params, and decode redirect details locally.
Percentage Calculator
Solve percent-of, growth, discount, and reverse percentage problems.
Age Calculator
Find exact age, target-date age, and upcoming birthday countdowns.
Date Difference Calculator
Measure time spans across dates, weekdays, and total hours.
Loan Calculator
Estimate monthly loan cost, total interest, and payoff timing.
Mortgage Calculator
Plan home payments with taxes, insurance, HOA, and PMI.
Discount Calculator
Estimate sale price, stacked coupon savings, and tax impact.
Tip Calculator
Split bills, compare tip rates, and round easier-to-pay totals.
BMI Calculator
Use metric or imperial input for BMI and healthy-weight checks.
Calorie Calculator
Estimate maintenance calories and simple goal-based targets.
Pace Calculator
Plan runs with pace, finish time, and distance conversions.
Compound Interest Calculator
Estimate investment or savings growth with recurring contributions.
Markup Calculator
Compare cost, selling price, margin, markup, and profit.
Working Days Calculator
Count weekdays and estimate due dates from business-day offsets.
Due Date Calculator
Estimate due date, trimester stage, and milestone weeks quickly.
GPA Calculator
Compute GPA from letter grades and course credits.
Grade Calculator
Track weighted class categories and required target scores.
Unit Converter
Switch across common metric and imperial unit systems.
Time Duration Calculator
Compare times, add durations, and subtract clock spans.
Fuel Cost Calculator
Estimate gas cost from distance, efficiency, and price.
Hours Calculator
Calculate shift totals, break deductions, and overtime hours.
Sales Tax Calculator
Estimate tax amount, pre-tax total, and full checkout cost.
Final Grade Calculator
Estimate the final exam score needed for your target grade.
Currency Converter
Convert offline FX pairs with editable rates and reverse conversion.
Baby Age Calculator
Show a baby's age in days, weeks, months, and simple milestones.
Calories Burned Calculator
Estimate calories burned across common activities and durations.
Body Fat Calculator
Estimate body fat percentage from height and body measurements.
Macro Calculator
Convert daily calories into macro grams using preset or custom splits.
Protein Calculator
Estimate protein per day and per meal using goal-based multipliers.
Water Intake Calculator
Plan hydration needs with exercise and climate adjustments.
Pregnancy Weight Gain Calculator
Estimate total and week-based gain ranges for singleton pregnancy.
Ovulation Calculator
Project fertile window and ovulation timing from cycle dates.
Conception Date Calculator
Estimate conception timing from due date, birth date, or LMP.
Take Home Pay Calculator
Estimate annual and monthly take-home pay after simple deductions.
Commission Calculator
Calculate payout from sales, commission rate, split, and base pay.
Profit Margin Calculator
Review gross profit, markup, and target selling-price scenarios.
Break Even Calculator
Estimate the sales volume needed to cover fixed costs.
Pay Raise Calculator
Translate raises into new salary, monthly increase, and percentage.
Hourly to Salary Calculator
Convert hourly wage into weekly, monthly, and annual totals.
Biweekly Mortgage Calculator
Compare annual mortgage cash flow under biweekly vs monthly plans.
Interest Rate Calculator
Back-calculate a simple annual rate from growth over time.
APR Calculator
Estimate annualized borrowing cost including upfront fees.
Debt Payoff Calculator
Estimate debt-free timeline and interest with extra payments.
Savings Goal Calculator
Calculate the monthly savings needed to reach a target amount.
Retirement Calculator
Project long-term retirement savings growth with monthly contributions.
Sales Tax by State Calculator
Compare state tax presets, local add-ons, and tax-included totals.
Inventory Turnover Calculator
Review turnover ratio, average inventory, and days inventory outstanding.
Coupon Savings Calculator
Estimate stacked coupon savings, tax, and final checkout total.
Return on Investment Calculator
Calculate ROI, net gain, annualized return, and return multiple.
Gross Margin Calculator
Estimate gross margin, gross profit, and target selling price.
Markup Percentage Calculator
Solve markup percentage, selling price, profit, and margin side by side.
Debt to Income Ratio Calculator
Estimate front-end and back-end DTI for mortgage or loan planning.
Down Payment Calculator
Plan cash needed, financed balance, LTV, and PMI threshold exposure.
Business Days From Today Calculator
Move forward or backward by workdays while skipping weekends.
Semester Grade Calculator
Estimate end-of-semester grade from weighted category scores.
Weighted Average Calculator
Calculate weighted averages for grades, KPIs, and scorecards with category weights.
Overtime Pay Calculator
Estimate regular pay, overtime premium, and weekly gross wages from hourly shifts.
Invoice Due Date Calculator
Calculate invoice due dates from issue date and payment terms like net 15, 30, or 45.
Net Income Calculator
Estimate net income, total expenses, operating profit, and profit margin.
Sales Commission Calculator
Calculate tiered sales commission with quota accelerators and split rules.
Paycheck Calculator
Estimate gross pay, withholding, deductions, and take-home paycheck totals.
Margin vs Markup Calculator
Compare margin and markup side by side and solve target price scenarios.
Customer Acquisition Cost Calculator
Calculate CAC from spend, payroll, tools, and new customers acquired.
Customer Lifetime Value Calculator
Estimate customer lifetime value from order value, frequency, margin, and retention.
Operating Margin Calculator
Calculate operating income and operating margin from revenue and costs.
Attendance Percentage Calculator
Calculate attendance percentage and how many more sessions you can miss.
Test Score Percentage Calculator
Convert raw test score into a percentage, pass result, and letter-grade estimate.
✅ Why Toolkit.Fun
The goal is simple: practical features, clear UI, and no unnecessary friction.
Fast by default
Static pages load quickly and work well even on simple hosting setups.
Local-first processing
Data-focused tools are designed to run in your browser whenever possible.
Built for practical tasks
Each page is meant to solve a specific workflow problem quickly and clearly.
🚀 Planned Next
The next tools expand the same fast, browser-first workflow for common developer needs.
Inventory Days Calculator
Estimate days inventory outstanding from stock balance and cost of sales.
Utilization Rate Calculator
Calculate billable utilization from available hours, billable hours, and targets.
Contribution Margin Calculator
Estimate contribution margin, ratio, and unit economics after variable costs.
❓ Frequently Asked Questions
What kind of tools will Toolkit.Fun include?
Toolkit.Fun now spans developer workflows plus high-intent utility searches across taxes, pricing, ROI, payroll, CAC/LTV, margin analysis, education score tracking, business-day math, shopping savings, and fast browser-based calculators.
Does Toolkit.Fun require an account?
No. The goal is to keep common utility workflows fast and accessible, with no signup wall for simple tasks.
Will these tools stay lightweight?
Yes, but lightweight does not mean overly simple. The plan is to keep static pages fast while still covering the options users actually expect.