Free, fully private tools with no registration and no limits
A platform with 341 free tools. Here you will find everything you need: from unit converters, through file and text formatting, to an email signature generator and a photo editor. All of it without creating an account, without limits and with full privacy of your data and files.
How do our tools work and what makes them different?
Your files stay on your own computer
Privacy is a basic thing for us, so we built every tool to calculate and process files on your own computer. All the work on your files and data happens on your machine, directly in your browser. We send nothing to a server, because everything is processed locally.You use them as many times as you want
Our tools have no limits, so you can use them as many times as you want. Everything is processed by your computer in real time, so the tools show the result straight away. You can, for example, run fifty photos through a converter one after another on a single day, and do exactly the same the next day. There are no restrictions and no limits.You open the tools without creating an account
Every tool is available right away. We have no premium version and no options hidden behind account registration — we simply do not run such a system, so you get all the features in the free version, without creating an account and without logging in. The version you see is complete from the first second and has every function.Tools and texts written for your country
We translate every element of a tool: field names, buttons, units and messages. Thanks to that you can comfortably use the tool in your own language. We write the texts under the tools separately for each country and adapt them to local realities and history. In the English version you will therefore find the standards, historical units and examples used in the United States and the United Kingdom, so an ordinary conversion can teach you something interesting as well.
Fix your photos in Helios, a free editor in your browser
Helios is a free photo editor that you open in your browser like any web page, with nothing to install and no account. You can brighten a photo that came out too dark, remove a yellow or blue tint, crop it and level a crooked horizon, then sharpen it and reduce noise. There are 100 ready-made filters, and you can copy the settings from one photo to a whole set, such as all the photos from a wedding. It opens photos from your phone and RAW files from your camera, and it works fully privately, because it processes your files in your browser.
Open Helios63 tools
Images
Format conversion (62 tools)
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PNG to JPG
Convert PNG files to JPG in your browser. No file limits, no signup, no server uploads.
WebP to JPG
Convert WebP files to universally compatible JPG. Works in every app and platform.
AVIF to TIFF
Convert AVIF files to TIFF format. Free, private, unlimited. Works in your browser.
Base64 to Image
Decode Base64 strings to images. Preview and download in your browser. Free, no registration.
Editing & creation (1 tool)
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Favicon generator
Create a complete favicon.ico set for your website from one image. All required sizes, no login.
48 tools
Data
Format conversion (8 tools)
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CSV to JSON
Convert CSV to JSON format. Automatic parsing and formatting. Free, no registration.
JSON to CSV
Convert JSON to CSV format. Automatic parsing and formatting. Free, no registration.
XML to JSON
Convert XML to JSON format. Automatic parsing and formatting. Free, no registration.
JSON to XML
Convert JSON to XML format. Automatic parsing and formatting. Free, no registration.
YAML to JSON
Convert YAML to JSON format. Automatic parsing and formatting. Free, no registration.
JSON to YAML
Convert JSON to YAML format. Automatic parsing and formatting. Free, no registration.
HTML to Markdown
Convert HTML or a whole web page to Markdown with GFM tables for GitHub and Obsidian.
Data size (23 tools)
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B to KB
Convert bytes to kilobytes and back. 1 KB is 1,024 bytes, with a formula and a conversion table.
bits to B
Convert bits to bytes. A byte has 8 bits, so 64 bits are 8 bytes and 1 bit is 0.125 bytes.
EB to ZB
Convert exabytes to zettabytes. 1,024 EB make 1 ZB in the binary standard and 1,000 EB in the decimal one.
GB to GiB
Convert gigabytes to gibibytes. 1,000 GB is 931.32 GiB, which is why a 1 TB drive shows 931 GB in Windows.
GB to MB
Convert gigabytes to megabytes and back. 1 GB is 1,024 MB, with a formula and a conversion table.
GB to TB
Convert gigabytes to terabytes and back. 1 TB is 1,024 GB, with a formula and a conversion table.
GiB to GB
Convert gibibytes to gigabytes. 1 GiB is exactly 1.073741824 GB, so 16 GiB of RAM equals 17.18 GB.
KB to B
Convert kilobytes to bytes and back. 1 KB is 1,024 bytes, with a formula and a conversion table.
KB to MB
Convert kilobytes to megabytes and back. 1 MB is 1,024 KB, with a formula and a conversion table.
MB to GB
Convert megabytes to gigabytes and back. 1 GB is 1,024 MB, with a formula and a conversion table.
Transfer speed (11 tools)
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Gbps to Mbps
Convert gigabits per second to megabits per second. The tables cover rates from 0.1 to 100 Gbps and the rates of Ethernet ports and USB connectors.
Gbps to Tbps
Convert gigabits per second to terabits per second. A table lists Ethernet rates from 1 Gbit/s to 1.6 Tbit/s with the standard behind each.
kbps to Mbps
Convert kilobits per second to megabits per second. The tables cover values from 56 kbps upwards and the bitrates of music, video calls and streams.
MB/s to Mbps
Convert megabytes per second to megabits per second. The tables cover 0.1 to 1,250 MB/s and the Ethernet port a given download speed needs.
Mbps to Gbps
Convert megabits per second to gigabits per second. The tables cover rates from 50 to 30,000 Mbps and the line rates of GPON and XGS-PON fibre.
Mbps to kbps
Convert megabits per second to kilobits per second. The tables give connection speeds and the rates Netflix, YouTube and video calls ask for.
Mbps to MB/s
Convert megabits per second to megabytes per second, in decimal or the way browsers show it. The tables cover 1 to 10,000 Mbps and Ethernet ports.
Pbps to Tbps
Convert petabits per second to terabits per second. A table lists submarine cable capacities and laboratory records.
Tbps to Gbps
Convert terabits per second to gigabits per second. A table gives how many 100, 400 and 800 Gbit/s ports add up to a link of a given size.
Tbps to Pbps
Convert terabits per second to petabits per second. A table shows the capacity at which petabits become the easier unit.
Numbers & time (6 tools)
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Unix to date
Convert a Unix timestamp in seconds or milliseconds to a date and time, in UTC or in your local time.
Date to Unix
Convert a date and time to a Unix timestamp in seconds, in UTC or in your local time.
Roman to number
Turn a Roman numeral or a Roman numeral date into regular numbers. The converter also reads the IIII form and letters with a bar over them.
Number to Roman
Write any number or date in Roman numerals, from 1 to 3,999,999. Numbers from 4,000 get a bar over the letters.
177 tools
Measurements
Length (67 tools)
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au to km
Convert astronomical units to kilometers. 1 au is exactly 149,597,870.7 km, and the tables give planet distances from JPL and scale model ratios.
cm to dm
Convert centimeters to decimeters. Ten centimeters make one decimeter. Ready-made tables, everyday object sizes and a spreadsheet formula.
cm to ft
Convert centimetres to feet and inches. Height table by the centimetre, older feet compared, spreadsheet formula.
cm to in
Convert centimeters to inches. Height, clothing sizes, TV screen size, luggage dimensions.
cm to km
Convert centimeters to kilometers. Read distance off a map scale, scientific notation, ready-made tables and a spreadsheet formula.
cm to m
Convert centimetres to metres. Ready-made table, everyday dimensions and what one centimetre means at scale 1:100.
cm to mm
Convert centimetres to millimetres. Ready-made table, ring sizes for the UK and the US, and how to measure a finger.
cm to yd
Convert centimeters to yards and read the result in yards and inches too. A table with the inch notation, old length measures and a spreadsheet formula.
dm to cm
Convert decimeters to centimeters. A decimeter is 10 centimeters. Ready-made tables, the metric ladder and the places the decimetre is really used.
dm to km
Convert decimeters to kilometers. Ten thousand decimeters make one kilometer. Ready-made tables, the result in kilometres and metres, and a formula.
dm to meters
Convert decimeters to meters. Ten decimeters make one meter, so 77.8 dm comes to 7.78 m. Ready-made table of values and a spreadsheet formula.
dm to mm
Convert decimeters to millimeters. A decimeter is 100 millimeters, so 3.5 dm is 350 mm. A table of values and the building module that equals one decimeter.
Weight (43 tools)
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carats to g
Convert carats to grams. Stone weights in grams, milligrams and points, plus gold karat marks.
dg to kg
Convert decigrams to kilograms and see where the decigram sits among the metric units.
g to carats
Convert grams to carats. Fractions of a gram, pearl trade units and the step of a jeweller’s scale.
g to grains
Convert grams to grains. Decimal grams, a pearl-grain switch, and English and jewellery units in grains.
g to lb
Convert grams to pounds. Results in pounds and ounces, birth weights, package sizes and a 500 g pound switch.
g to mcg
Convert grams to micrograms. Fractions of a gram, lab balance readings and scientific notation in the field.
g to t
Convert grams to tons. Pick metric, short or long tons and see how many items of a given weight add up to one ton.
grains to g
Convert grains to grams. Bullet and arrow weights, a pearl-grain switch and the grain in older systems of measurement.
Volume (57 tools)
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barrels to gallons
Convert barrels to gallons. Pick an oil or beer barrel and a US or imperial gallon.
barrels to l
Convert barrels to litres. An oil barrel is 158.987 litres, and beer barrels differ between the US and the UK.
centilitres to l
Convert centilitres to litres. A centilitre is 0.01 litre, or 10 millilitres, with bottle and can sizes in a table.
centilitres to ml
Convert centilitres to millilitres. A centilitre is 10 millilitres, with bottle sizes and bar measures in a table.
cl to oz
Convert centilitres to fluid ounces. US or UK ounce switch, bottle sizes and bar measures.
cups to gallons
Convert cups to gallons. Sixteen cups make one US gallon, and the switcher adds the dry gallon and the imperial one.
cups to l
Convert cups to litres. One US cup is 0.2366 l, and four metric cups make exactly one litre.
cups to ml
Convert US cups to millilitres. The field takes fractions like 3/4, plus a 55-row table and tablespoon counts.
cups to ounces
Convert cups from an American recipe to fluid ounces. One US cup is exactly 8 fl oz, and the switcher adds the labelling and metric cups.
cups to pints
Convert cups to pints. Two cups make one US liquid pint, and the switcher adds the dry pint and the imperial pint.
deciliters to ml
Convert decilitres to millilitres. One decilitre is 100 ml, with a table from 0.05 dl and tablespoon equivalents.
decilitres to l
Convert decilitres to litres. A decilitre is 0.1 litre, that is 100 millilitres, with a ready table.
Speed (1 tool)
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units of speed
Convert any of 33 speed units to any other: mph, km/h, m/s, feet per second, knots, the Mach number, running pace per mile and the speed of light.
Pressure (9 tools)
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atm to psi
Convert atmospheres to psi. One atmosphere is 14.6959 psi. The tables give diving depth in atmospheres and the atmosphere in other units.
psi to atm
Convert psi to atmospheres. One psi is 0.068046 atmospheres. The tables give real air pressure with the WMO records and gauge readings in absolute atmospheres.
bar to psi
Convert bar to psi. The tables give scuba cylinder, hydrogen refueling and espresso pressures, with the standard and technical atmosphere alongside.
psi to bar
Convert psi to bar. One table covers tires and 3,000 psi cylinders, another sets gauge psig against absolute psia.
kPa to psi
Convert kilopascals to psi. The tables give tire pressure warning thresholds from UN Regulation No. 141 and MAP sensor readings as gauge psi.
psi to kPa
Convert psi to kilopascals. A table gives tire pressures with the warning threshold from the US standard FMVSS 138, and the steps show a spreadsheet formula.
bar to kPa
Convert bar to kilopascals. One table covers 58 values from 0.1 to 1,000 bar, another places the bar among the pascal, millibar, megapascal and atmosphere.
kPa to bar
Convert kilopascals to bar. One table covers 50 values from 1 to 10,000 kPa, another gives the water pressure required by building rules in four countries.
28 tools
Print & screen
Pixels & DPI (11 tools)
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m to px
Convert meters to pixels at any DPI. For banners, billboards and large-format graphics.
px to ft
Convert pixels to feet at any DPI. Check the file covers the size before it goes out.
Typographic units (17 tools)
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cm to pt
Convert centimetres to points, the unit Word and layout programs use for font size.
in to pt
Convert inches to points for page sizes, margins and bleed. The selector gives PostScript, TeX and Didot points.
pt to cm
Convert points to centimetres and see how big a font size prints. The selector also covers TeX and Didot points.
pt to in
Convert points to inches and see how tall a font size really prints. The selector also covers TeX and Didot points.
pt to mm
Convert points to millimeters and see how tall letters and how thick lines come out in print.
7 tools
Text
Text analysis (6 tools)
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Meta title & description checker
Check title and description length in pixels. Live Google preview and optimization tips.
Word & character counter
Count words, characters with and without spaces, sentences, paragraphs and the average sentence length.
Flesch Reading Ease score
Score how easy a text is to read from 0 to 100 and see its grade level.
Generators (1 tool)
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Lorem Ipsum Generator
Free Lorem Ipsum generator — 8 text styles, paragraphs, sentences or words. Copy in one click.
16 tools
Colours
Palettes & contrast (3 tools)
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Color palette generator
Generate 17 palettes from one color: monochromatic, complementary, triadic and more. HEX codes.
Color contrast checker
Check text and background contrast per WCAG 2.1 AA and AAA. Automatic color correction.
Image color extractor
Extract dominant colors from a photo or logo. Ready HEX and RGB codes to copy.
Colour conversion (13 tools)
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CMYK to HEX
Turn four CMYK values from a brand guide into a HEX code for your website and CSS.
HEX to CMYK
Turn a HEX code from a website or Figma into the four CMYK inks for a print job.
HEX to HSL
Turn a HEX code into hue, saturation and lightness in CSS notation or the Office scale.
RGB to CMYK
Turn a screen RGB colour into the four CMYK inks before you send a file to press.
RGB to HSV
Turn RGB values into HSV hue, saturation and value in degrees, on the OpenCV scale or as 0–1 fractions.
2 tools
Business
Company materials (2 tools)
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Frequently asked questions about our tools
How much do the tools cost?
Nothing. All the tools are completely free.
Are my files sent to a server?
No. The tools calculate and process data entirely in the browser, on your own device.
Do I need an account?
No, we do not run account registration at all. You open the tool page and can start using it right away.
Is there a usage limit?
No. You can use every tool as many times as you want. There are no limits and no restrictions.
Are the tools available in other languages?
Yes, the tools are available in 8 languages: English, Polish, German, Spanish, French, Portuguese, Italian and Czech. We adapt each version to the country where people use it, so the examples, units and standards come from the local context.