First of all put manifest.json file in folder, and dimension of icon must be 128x128.
- Open Google Chrome.
- Put
chrome://extensions/
in serarch bar, press Enter. - Edit your manifest.json file's fields like "name": "Extension Name", "default_popup": "file_name.html to open on clicking extension pinned".
- Click "Developer mode" at top right corner see above screenshot.
- ...then click "Load unpacked" at top left in above pic.
- Select Folder and pin on extension bar of chrome tab.
- Congratulation !!! ...you made your own CUSTOM chrome extension.