Lambda Guru

Free software tools, built by one developer

Hi, I'm Code. Lambda Guru is my software hub. I got fed up with the crazy prices charged for simple software, so I build my own tools and share them here for free. The only catch is that I display ads to help pay for the hosting costs.

Use whatever helps you. The tools run in your browser, your files stay on your device, and you do not need an account. I add new tools as I finish them.

Browse the tools About me

Search all 128 tools by name, task, or file type.

Audio Tools

Change the format of a recording, keep just the part you want, or join several files into one track.

Convert and Trim

  • Audio Converter

    Convert one or many audio files to MP3, WAV, FLAC, and more.

  • Audio Cutter

    Keep one section of an audio file using a waveform editor.

  • Audio Joiner

    Join audio files end to end into a single track.

  • Audio Reverser

    Play a track backwards with a Web Audio preview.

  • Silence Remover

    Trim silence from ends or shorten pauses on a marked waveform.

Record and Analyze

Sound and Levels

Color and Design

Pick and convert colors, check contrast, and build simple palettes.

Palettes and Graphics

Pick and Check

Developer and Text

Generate codes, compare files and text, and convert data locally.

Data and Encoding

Files and Security

QR and Barcodes

Text and Writing

  • Case Converter

    Convert text to upper, lower, title, sentence, camel, snake, kebab, or constant case.

  • Markdown Previewer

    Write Markdown and preview sanitized HTML.

  • Regex Tester

    Test JavaScript patterns, flags, groups, and replacements in a worker.

  • Text Diff

    Compare two texts by line or word, inline or side by side.

  • Word Counter

    Count words, characters, sentences, paragraphs, and common words.

GIF Tools

Make an animated GIF smaller, change its dimensions, or go between GIF and video.

Create and Convert

Effects and Overlays

Frames and Timing

  • GIF Cutter

    Keep one part of a GIF, or split it into two files.

  • GIF Frame Editor

    Delete, duplicate, reorder, and retime the frames of a GIF.

  • GIF Frame Extractor

    Save GIF frames as separate PNG, JPG, or WEBP images, or a zip.

  • GIF Inspector

    See the frames, delays, palettes, and settings inside a GIF.

  • GIF Joiner

    Join GIFs one after another, side by side, or stacked.

  • GIF Reverser

    Play a GIF backwards, or forward then back as a boomerang.

  • GIF Speed Changer

    Speed up or slow down a GIF, or give every frame one delay.

Size and Shape

Image Tools

Change a picture's format, pixel size, file size, or color.

Color and Effects

Convert and Optimize

Crop and Layout

Pico Portal OS

Privacy and Review

Text and Sharing

PDF Tools

Combine images into a PDF or edit PDF pages in this tab.

Convert

  • Images To PDF

    Combine PNG and JPG images into one PDF with page previews.

  • PDF To Images

    Export PDF pages as PNG, JPG, or WEBP in a zip.

Edit and Sign

  • PDF Metadata Editor

    Edit or clear PDF title, author, subject, keywords, and dates.

  • PDF Page Numbers

    Add page numbers with position, format, and skip options.

  • Sign PDF

    Place a drawn, typed, or uploaded signature picture on a PDF.

  • Watermark PDF

    Add a text or image watermark with opacity and page range.

Organize Pages

  • Merge PDFs

    Join several PDFs into one file with reorderable previews.

  • PDF Page Organizer

    Reorder, rotate, delete, and insert blank PDF pages.

  • Split PDF

    Split a PDF by ranges, every N pages, or selected pages.

SVG Tools

Recolor the shapes in a vector file, give it a new size, trace a picture into a vector, or export an SVG as PNG, JPG, WebP, or BMP.

Convert and Export

  • Image To SVG

    Trace logos and line art into one-color vector SVGs.

  • SVG Sprite Builder

    Combine SVG icons into one sprite with editable symbol ids.

  • SVG To Code

    Turn an SVG into React, Angular, CSS, base64, or URL-encoded code.

  • SVG To Raster

    Render SVGs to PNG, JPG, WebP, or BMP at a set pixel size.

Edit and Optimize

Video Tools

Convert a clip to MP4 or WebM, cut or crop it, shrink it, resize it, or adjust its colors.

Audio Track

Convert and Compress

  • Media Info

    Inspect codecs, bitrate, resolution, and tags locally.

  • Video Converter

    Convert MP4, MOV, and WEBM videos to WebM or MP4 in a batch.

  • Video Optimizer

    Shrink a video as an H.264 MP4 with one quality slider.

  • Video Resizer

    Set a new width and height in pixels, saved as MP4.

Frame and Look

Record and Capture

Text and Subtitles

Trim and Timing

  • Video Cutter

    Keep one part of a video with a fast copy cut or an exact re-encode.

  • Video Joiner

    Join videos one after another; stream-copy when they match.

  • Video Loop

    Repeat a video by count or length, or make a boomerang.

  • Video Reverser

    Play a video backwards, or make a boomerang loop.

  • Video Speed Changer

    Speed up or slow down a video from 0.25x to 4x.

What this site is

Lambda Guru is a small software hub that I build and run by myself. There is no company behind it and no team. I make the tools, put them here, and anyone can use them.

Changing a file's format, trimming a recording, or shrinking a video are small jobs, and too much of the software that does them asks for a monthly fee or hides the useful part behind a paid plan. I would rather build a tool once and share it.

How the tools work

Every tool on this site runs inside your browser. When you pick a file, the page reads it straight from your device, does the work there, and hands you back a new file to save. Your file is not sent to a server, so there is no upload to wait for and no copy of it left anywhere else.

The image and SVG tools use what your browser already has built in. Most of the audio, GIF, and video tools use FFmpeg, an open source media program, in a version made to run in the browser. The first time you use one of those, the page has to download the FFmpeg engine first, and that can take a few seconds.

Because the work happens on your device, performance depends on the hardware you are using. Large or long videos can take longer to process than they would in a desktop editor, and very large files may use more memory than some phones or older computers can handle. These tools are best for images, audio files, and shorter video clips.

What you can expect here

  • Free to use. Open a tool and use it as often as you like.
  • No sign-up. You do not need an account to use a tool.
  • Your files stay with you. The tools work on your device, and nothing you open is uploaded.
  • A guide with every tool. Each tool page explains its formats, settings, and limits in plain words.

More on the way

The site is not finished, and I do not plan for it to be. I add new tools as I finish them, and I keep fixing and improving the ones already here.

If something is broken, or you need a tool that is not here yet, tell me. My contact details are on the About page, and the FAQ answers the common questions.

Supporters

Thanks to everyone below for supporting my projects and helping keep the site going. Be sure to click through their links as well and check out what they're working on. If you'd like to become a supporter with your own link featured here, click the link below!

Found something useful? You can support the site or add your own links here as a supporter, and be listed on pip-boy.com as well.