Free Online Tools

Encode plain text into Base64 or decode Base64 strings back into readable UTF-8 text.

Turn an uploaded or pasted image into a Base64 data URL, or paste Base64 back into a previewable image you can download. Works with PNG, JPEG, GIF, WebP, and other common image formats.

Inspect PEM, CER, CRT, DER, and PFX/P12 certificates locally. View subject, issuer, validity, fingerprints, SANs, key usage, and full certificate chains.

Way too many people use Certified Mail when they should be using Certificate of Mailing instead. Where Certified Mailing gives you proof of delivery (and the date/time it was delivered) - a Certificate of Mailing provides proof of <em>the date the package was mailed</em>. So anything that requires the package be "received by" a specific date <strong>does in fact</strong> justify Certified Mail. However, anything that has a deadline of being "mailed by" a specific deadline (eg: all tax filings and payments in the US) only need a Certificate of Mailing which costs a small fraction of Certified Mail. With this tool here you can generate a printable PDF file with up to 8 pre-populated USPS Certificate of Mailing forms so you don't find yourself standing to the side of the line at the Post Office scrambling to fill in the addresses by hand in the too-small lines on the silly little PS3817 form.

Created as a tool to remove myself from the edit-update-fix loop, this simple tool will encode the text of your choice into multiple encodings.

A simple tool to view the color from a given code and get the color in other formats.

Inspired by countless conversations over my career about what information every website you visit actually knows about you, here is a brief example of information my web server knows about you and your connection with just a few lines of code. This is just the tip of the iceberg compared to what trackers (website plugins which follow you from one website to another running analytics on your browser behavior) know about you.

Validate standard 5- and 6-field cron expressions, inspect each field, read a plain-language summary, and preview upcoming run times in your chosen timezone.

Convert Unix timestamps, ISO 8601 strings, SQL datetimes, and common display formats in either direction. Shift between timezones or rewrite strings like YYYY-MM-DD into MMM D, YY.

Inspired by the Tubbs/Sonoma Complex Fires of 2017, this interactive map of heat signatures enables one to easily see where wildfires are, monitor their progress and measure their size and distance from you or those you care about. The data comes from NASA and is updated a couple times a day.

Turn any phrase into the classic table-flip ASCII emoticon — express your frustration and flip what's bothering you!

An online icon generator to quickly create icons with a letter or two.

A utility to decode and deserialize a JWT token to inspect the data inside

At the request of an elementary school teacher trying to adapt to distance learning, this online tool allows you to quickly create a collection of customized image tiles with letters or numbers on them.

Write GitHub-flavored markdown and preview the rendered HTML locally. Supports tables, task lists, fenced code blocks, and Mermaid diagrams with sanitized output.

Pick a classic meme template, type your caption, and download a share-ready image. Supports multi-line text and a handful of pre-built formats like Yo Dawg and Say It Again.

Create flowcharts, sequence diagrams, class diagrams, Gantt charts, and more with live preview, examples, and a built-in syntax cheatsheet.

A handy little utility to quickly convert between JSON, YAML, TOML and MsgPack/MessagePack serialization.

Convert integers between binary, octal, decimal, hexadecimal, and any base from 2 through 36. Auto-detect 0b, 0o, and 0x prefixes or choose the input radix explicitly.

Inspired by the old Photobooths you used to find at the mall (and occasionally still do), this little app enables you to make your own photostrip from any photos you want and works on mobile quite well.

Inspired purely by the frustration of having to help others find their own tools for a rare or one off need to make JSON readable

Format or compress JSON, XML, HTML, SQL, and CSS locally in your browser. Switch between readable indentation and compact minified output.

Quickly create a QR code image from a URL. You can actually paste any text and any QR camera app will be able to read it, but URL's are the most common and easiest to use.

Test regular expressions against sample text with support for JavaScript, PCRE, grep BRE, grep ERE, Python, and POSIX-style flavors, plus notes on which languages use which implementation.

Originally created to provide images to an automated out-of-office slack integration, this enables you to create an old school custom Wanted style poster from any picture you want.

Inspired by the Grand Theft Auto screen when one is killed or arrested, this tool lets you create a similar image from your own photos with custom text.

Flexing the power of QR codes this app you can create custom Wifi Placards to enable anyone with a camera to join your wifi network with zero typing and display the credentials to anyone on a device without a camera. Enter your credentials, select your page size and download a zip file with PDF's you can print out, hang up or even mount in a picture frame (4x6 or 5x7).