Converters
Converters turn a value or a file from one format into another. All 43 run in your browser, which means a PDF, an image or an audio file you convert here is never uploaded to a server.
43 tools
Data and text formats
- Binary ConverterConvert between binary, octal, decimal and hexadecimal in every direction, with digit grouping.
- CSV to JSON ConverterConvert CSV to JSON with a proper RFC 4180 parser that handles quoted fields and embedded commas.
- HTML to Text ConverterConvert HTML to text by stripping tags and decoding entities, with the option to keep paragraph breaks so the result reads as prose rather than one long line.
- IPv4 to IPv6 ConverterShow the mapped, compatible and 6to4 IPv6 forms of an IPv4 address, with the deprecated ones marked.
- JSON to CSV ConverterFlatten nested JSON into CSV, with dotted column names and a union of keys across all records.
- Letters to Numbers ConverterConvert letters to numbers and back using the A1Z26 scheme, where each letter maps to its position in the alphabet. Both directions run in your browser.
- Number to Words ConverterWrite numbers out in words in British or American style, including decimals and negatives.
- Punycode ConverterConvert international domain names to and from punycode, with a homograph-attack warning.
- Text to ASCII Codes ConverterConvert text to decimal, octal, hexadecimal or binary character codes, and back again.
- Text to HTML ConverterConvert plain text to HTML with paragraph detection, line breaks or escaping only.
Files, images and PDFs
- Add Page Numbers to PDFAdd page numbers to PDF files in your browser, choosing the corner, the number format and the page the count starts from. Nothing is uploaded to a server.
- Add Watermark to PDFAdd watermark to PDF pages in your browser: text stamped across every page, with opacity, size and rotation under your control and no upload step at all.
- Base64 to Audio ConverterDecode base64 audio to a playable file in five formats, with a player and a download.
- Base64 to Image ConverterBase64 to image download: decode a base64 string or data URL back to an image you can view and download.
- Crop PDFTrim margins from PDF pages by setting a crop box, in points, on any page range.
- Extract Images from PDFExtract images from PDF files at the resolution they were stored, page by page. This recovers the embedded photographs rather than rendering whole pages.
- HTML to Image ConverterConvert HTML to image files in the browser, rendered through SVG foreignObject to a downloadable PNG, with the limits of that approach stated up front.
- Image ConverterThe image converter moves a file between PNG, JPEG and WebP, accepts SVG input, and shows the size of the result beside the original so the trade is visible.
- Image to PDF ConverterCombine PNG and JPEG images into a multi-page PDF in your browser, with page-size options.
- Image to WebP ConverterConvert an image to WebP from PNG, JPEG, GIF or BMP, entirely in your browser, with a quality slider and a before-and-after size comparison for every file.
- Markdown to PDF ConverterConvert Markdown to a formatted PDF with headings, lists and code blocks, in your browser.
- Merge PDFMerge PDF files into a single document in your browser, with the order under your control. Nothing is uploaded, so the files never leave your machine.
- PDF to Image ConverterConvert PDF to image files: render pages to downloadable PNGs at up to 4x resolution, in your browser.
- Rotate PDFRotate PDF pages by 90, 180 or 270 degrees, either the whole document or a chosen range. The change is lossless because only a rotation flag is rewritten.
- Screen RecorderRecord a screen, window or tab to a WebM file in the browser, with no upload and no install.
- Split PDFSplit a PDF by pulling a page range into a new document, or break the file into one PDF per page. Both run in your browser with nothing uploaded anywhere.
- SVG to JPG ConverterConvert SVG to JPG by rasterising the vector at any size, with a background fill you choose, since the JPEG format has no alpha channel to carry transparency.
- Text to Handwriting ConverterRender text as handwriting on ruled paper, with per-character wobble, as a downloadable PNG.
- Text to PDF ConverterTurn plain text into a paginated PDF with word wrap, adjustable margins and A4 or Letter pages.
- Text to SpeechText to speech using the voices already installed on your device, with speed and pitch control. The synthesis runs locally, so no text is sent to a server.
- TIFF to JPG ConverterConvert TIFF to JPG in your browser, including multi-page TIFF files, which most browsers cannot display at all. Each page is exported as a separate JPEG.
- Voice RecorderA voice recorder that captures audio from your microphone and saves it as a WebM file. The recording stays in the browser and is never uploaded anywhere.
Colour
Units and measures
- Angle ConverterThe angle converter moves between degrees, radians, gradians, turns, arcminutes, arcseconds and NATO mils, with every conversion shown to full precision.
- Area ConverterConvert between 10 area units including hectares and acres, with the exact metric definitions.
- Data ConverterConvert data sizes across both decimal and binary prefixes, which is why your drive looks smaller than advertised.
- Length ConverterConvert between 12 length units, from nanometres to light years, using exact 1959 definitions.
- Speed ConverterConvert between km/h, mph, knots, m/s, ft/s, Mach and the speed of light.
- Temperature ConverterThe temperature converter moves between Celsius, Fahrenheit, Kelvin and Rankine, and refuses any value below absolute zero rather than returning nonsense.
- Volume ConverterConvert between 13 volume units, keeping US and Imperial measures separate as they genuinely are.
- Weight ConverterThe weight converter moves between metric and imperial mass units, and distinguishes the US short ton from the UK long ton, which differ by about 12 percent.
Dates and time
What the converters cover
The 43 converters split into five groups by what goes in. Twenty-two handle files, images and PDFs, including merging, splitting, cropping and rotating a PDF, and converting between image formats. Ten handle data and text formats, such as CSV to JSON and text to character codes. Eight handle units and measures, from length and weight to data size. One handles colour notation. Two handle dates and time.
File conversion happens on a canvas or through a PDF library loaded into the page, so the file stays in memory on your own machine. That is why a large file is limited by your available memory rather than by an upload cap, and why the tools keep working without a connection once the page has loaded.
Conversions that lose information say so on the page. Converting a PNG to JPEG discards transparency, and converting to a lossy format at a low quality setting cannot be undone by converting back.
Choosing between the converters
Start from what you are holding, not from the format you want, because several tools produce the same output from different inputs.
| What you have | Which converter |
|---|---|
| A PDF you want smaller or reordered | Split PDF removes pages, crop PDF trims margins. Cropping hides content rather than deleting it |
| Several PDFs to combine | Merge PDF, which keeps the order you arrange them in |
| An image in the wrong format | Image converter for PNG, JPEG and WebP, or the dedicated SVG and TIFF converters |
| Pictures that are inside a PDF | Extract images from PDF, which recovers the originals. PDF to image renders whole pages instead |
| A spreadsheet export to load into code | CSV to JSON, which uses an RFC 4180 parser so quoted commas survive |
| A measurement in the wrong unit | The 8 unit converters, each stating which conversions are exact and which are approximations |
Frequently asked questions
Are files uploaded to a server when I convert them?
No. Every converter reads the file with the browser FileReader API and processes it in the page. There is no server that receives the file, which is a property of how the site is built rather than a policy. Closing the tab discards the file and the result.
Why does converting a PNG to JPEG give me a black background?
Because JPEG has no alpha channel, so transparency has to become a solid colour. The converters fill transparent areas with white by default and let you choose a different fill. Converting back to PNG restores the alpha channel but not the pixels the fill replaced.
Is there a size limit on the files these converters accept?
The practical limit is your available memory, because the file is held in the page rather than streamed to a server. Files above 100 MB are refused by the multi-file tools, since a browser tab will not handle one reliably. A single large PDF often works well past that.
Do unit conversions here use exact factors or rounded ones?
Exact factors wherever an exact factor exists. One inch is defined as 25.4 mm, so length conversions are exact. Conversions between calendar units are approximations, because a month has no fixed length, and each of those tools states that on its own page.