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wtf is skaler?

terkelg/skaler — explained in plain English

Analysis updated 2026-07-17 · repo last pushed 2020-03-15

91JavaScriptAudience · developerComplexity · 1/5DormantSetup · easy

TL;DR

A tiny 329-byte JavaScript library that shrinks images in the browser before upload, using only the built-in Canvas API.

Mindmap

mindmap
  root((repo))
    What it does
      Resizes images
      Runs in browser
      No server needed
    Tech stack
      JavaScript
      Canvas API
      Zero dependencies
    Use cases
      Shrink photo uploads
      Profile picture tools
      Document scanning apps
      Social media uploads
    Audience
      Frontend developers
      Vibe coders
      App builders
      Web form designers

Code map

Detail Auto

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filefunction / class

Why would anyone build with this?

REASON 1

Shrink large phone photos in the browser before they're uploaded to your server.

REASON 2

Build a profile picture uploader that automatically resizes images to a target size.

REASON 3

Resize scanned documents to a specific width while keeping proportions intact.

REASON 4

Reduce storage costs by compressing user-uploaded images client-side before sending them.

What's in the stack?

JavaScriptCanvas API

How it stacks up

terkelg/skalerruanyf/user-tracking-demosjimliu/baoyu-design
Stars919190
LanguageJavaScriptJavaScriptJavaScript
Last pushed2020-03-152019-04-15
MaintenanceDormantDormant
Setup difficultyeasyeasyeasy
Complexity1/52/52/5
Audiencedeveloperdevelopervibe coder

Figures from each repo's GitHub metadata at analysis time.

How do you spin it up?

Difficulty · easy Time to first run · 5min
Open-source and free to use in your own projects, check the repo's license file for exact reuse terms.

Wtf does this do

Skaler is a tiny tool that shrinks images on your computer before you upload them to a server. Instead of sending a full-resolution photo to your server, you can use this library to make it smaller first, right in the user's browser. This saves storage space on your server, reduces how much data travels over the internet, and cuts down on the processing load your server has to handle. The way it works is straightforward. You give it an image file (the kind you get when someone picks a photo from their computer using a file input), tell it how you want to resize it, and it gives you back a smaller file. You can scale by percentage (make it half the size), resize to a specific width or height while keeping the image's natural proportions, or stretch it to exact dimensions. Everything happens on the user's device using vanilla JavaScript, no server communication needed for the resizing itself. This is perfect for apps where users upload photos: a social media feed, a profile picture uploader, a document scanning app, or any web form that accepts images. Instead of letting users upload massive 5MB phone photos, you can automatically shrink them to 500KB before sending, making the upload faster and keeping your storage bills manageable. The library is only 329 bytes, incredibly small, and has zero dependencies, so it adds almost no weight to your webpage. The project is intentionally minimal and focused on doing one thing well. It uses only built-in browser features (the Canvas API) and plain JavaScript, which means it works everywhere without needing to install extra packages. The README hints that the author plans to explore even faster approaches in the future using newer browser features, but for now, this strikes a balance between simplicity and performance that works in all modern browsers.

Yoink these prompts

Prompt 1
Show me how to use skaler to resize an image file from a file input down to 50% of its original size before upload.
Prompt 2
Write JavaScript using skaler to resize a user's uploaded photo to a max width of 800px while keeping proportions.
Prompt 3
Help me integrate skaler into my image upload form so large photos are shrunk client-side before hitting my server.
Prompt 4
How do I use skaler to stretch an image to exact fixed dimensions instead of keeping its aspect ratio?

Frequently asked questions

wtf is skaler?

A tiny 329-byte JavaScript library that shrinks images in the browser before upload, using only the built-in Canvas API.

What language is skaler written in?

Mainly JavaScript. The stack also includes JavaScript, Canvas API.

Is skaler actively maintained?

Dormant — no commits in 2+ years (last push 2020-03-15).

What license does skaler use?

Open-source and free to use in your own projects, check the repo's license file for exact reuse terms.

How hard is skaler to set up?

Setup difficulty is rated easy, with roughly 5min to a first successful run.

Who is skaler for?

Mainly developer.

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