CVAT is a really neat labelling platform, online + free on-premise w/ Docker.
(Github: cvat-ai/cvat: Annotate better with CVAT, the industry-leading data engine for machine learning. Used and trusted by teams at any scale, for data of any scale.)

I like it more than label studio for images, has more functions, but is also “heavier” / bulkier.

Love how it supports even 600mb 4-channel TIFF satellite images and is quite fast at that.

Bits:

• Enable auto-save every N minutes
• <C-a> for snipping polygons to existing polygon ponits
• “Backup project” to re-import later, “Export project” to get e.g. YOLO annotations