Turn any image into PNG file with a translucent pixel so that Twitter won't use JPEG for your image.
Try web version, download OSX app or build it for your platform from source.
Twitter use JPEG to any opaque image uploaded regardless of original file format (which drives me nuts 😖), exception is PNG with transparency. This app will turn a single pixel on top left corner to 99.6% opacity (hardly any different from original) and export as PNG.
Please see below for sample result, you can see opaque image upload gets pretty rough JPEG artifacts. (original tweet is here)
In order to run this from source, you'll need electron installed.
npm install -g electron
cd [repo's directory]
npm install
electron .
cd [repo's directory]
electron-packager . translucent --platform=darwin --arch=x64 --version=0.36.1 --icon=translucent.icns
I learned about Twitter's transparent image trick from @RavenWorks's twitimagefix. Thank you @matthewmcvickar for linking me to the project !