Free online tools for developers, musicians and everyday calculations

Decode Base64 back to readable text, in the standard or the URL-safe alphabet, entirely in your browser.

Encode text to Base64, in the standard or URL-safe alphabet, entirely in your browser.

Indent a stylesheet so you can read it, entirely in your browser. Nothing is renamed, shortened or normalised.

Turn a CSV table into a JSON array of objects, entirely in your browser.

Rewrite text as camelCase, snake_case, kebab-case, Title Case and six more, in your browser.

Count characters, words, lines, paragraphs and bytes as you type, and see how often each character occurs — entirely in your browser.

Turn a tempo into note durations in milliseconds, for straight, dotted and triplet values.

The notes of any chord, from a triad to a thirteenth, spelled the way you would write them.

Type the notes you are playing and find out what the chord is called, inversions included.

Move a chord chart from one key to another, keeping the layout and the spelling right.

Every key signature, its relative minor and its neighbours, arranged the way they relate to each other.

Any scale or chord drawn on the neck, in seventeen tunings or one you type yourself, right-handed or left.

How old someone is in years, months and days, and how long until the next birthday.

What a balance grows to over time, with or without regular contributions, and how much of it is interest.

How long between two dates: the exact number of days, and the same gap in weeks, months and years.

The price after a discount, what you save, and what a second discount on top actually comes to.

What an amount in one year is worth in another, from the World Bank consumer price index, for the countries and years it actually covers.

Work out the payment on a loan, what it costs in total, and how the balance falls year by year.

How much a given income can borrow, and what that plus a deposit actually buys once acquisition costs are paid.

What a property costs each month: the loan, the deposit, and the charges you pay alongside it.

What an extra payment saves — as a shorter loan, and as a smaller instalment, which are not the same amount.

Rent owed for a part month, under either of the two conventions leases actually use — and it says which one it applied.

Whether buying beats renting over the years you would stay, counting the money the deposit would otherwise have earned.

Gross, net and after-tax yield on a let property, and what is actually left each month once the loan is paid.

Area and perimeter of nine plane shapes, each one drawn to scale with the measurements you gave.

Count the ways to choose r things from n — with or without order, with or without repeats.

Solve ax³ + bx² + cx + d = 0 — all three roots, complex ones included, and whole ones written as whole numbers.

Add, subtract, multiply and divide fractions exactly, reduced and as a mixed number.

The greatest common divisor and least common multiple of two numbers or of a whole list.

Describe a list of numbers, with both the sample and the population standard deviation.

Convert between degrees, radians, gradians, turns, arcminutes and arcseconds.

Convert between square metres, square feet, hectares, acres and the rest.

Convert between bytes, kilobytes, gigabytes and their binary counterparts, which are not the same thing.

Convert between megabits per second, megabytes per second and every other bit and byte rate.

Convert between joules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, foot-pounds and electronvolts.

Convert between hertz, kilohertz, megahertz, gigahertz and revolutions per minute.

Body mass index with the WHO band it falls in, and the waist-to-height ratio that covers what BMI misses.

Training zones from a published estimate of maximum heart rate — with the spread that estimate carries.

Estimate a one-repetition maximum by four named formulas, so the spread between them is visible.

Turn km/h into minutes per kilometre and back, with miles, swimming and rowing splits beside them.

Every split for a target finish time — what the watch should say at each marker.

Predict your time at another distance from a recent result, by the Riegel formula.

Add or take away years, months, weeks and days from a date, with month ends handled the way people mean them.

Set a duration and let it run down, with an alarm at zero. Entirely in your browser.

Check whether a year is a leap year under the Gregorian rule, see why, and find the next ones.

Work and rest in alternating intervals, with every length adjustable. Entirely in your browser.

Time something to the hundredth of a second, with laps. Entirely in your browser.

Convert a date and time from one time zone to another, with the offsets and daylight saving actually in force that day.

What your electricity emits, using the carbon intensity of your own country's grid.

What an appliance costs to run, per day, per month and per year, at your own tariff.

Two electricity or gas offers compared on your consumption, with the point where the other one wins and whether off-peak pays.

How much your car really uses, from a fill-up and the distance driven: litres per 100 km, km per litre and miles per gallon.

What a journey costs in fuel or in electricity, and the two compared when you give both.

From two gas meter readings to kilowatt-hours and a cost, with the conversion figure your bill gives in m³ or cubic feet.