Blender Infinite Backups

infinite.py

bl_info = {
    "name": "Infinite Backups",
    "author": "Alistair Buxton <a.j.buxton@gmail.com>",
    "version": (1, 0),
    "blender": (2, 80, 0),
    "doc_url": "https://gist.github.com/ali1234/415c5ac863c5649c41a22fe061351a22",
    "tracker_url": "https://gist.github.com/ali1234/415c5ac863c5649c41a22fe061351a22",
    "category": "System",
}

import pathlib
import datetime

import bpy
from bpy.app.handlers import persistent


@persistent
def infinite_backups_save_handler(*args, **kwargs):
    # saving the file will trigger this hook again, so disable it first
    bpy.app.handlers.save_post.remove(infinite_backups_save_handler)
    
    # calculate the filename for the backup
    full_orig = pathlib.Path(bpy.data.filepath)
    path = full_orig.parent   # the directory
    name = full_orig.stem     # the name without extension
    suff = full_orig.suffix   # probably ".blend" but maybe something else?

    # get ISO 8601 UTC time as a string
    # guaranteed to be monotonic and alphanumeric sortable
    time = datetime.datetime.now().replace(microsecond=0).isoformat()

    # construct the backup filename
    full_new = path / (name + '-' + time + suff)
    
    # save a copy to the backup filename
    # copy=True so that it doesn't change the current active file
    bpy.ops.wm.save_as_mainfile(filepath=str(full_new), copy=True)
    
    # re-enable the hook for the next save
    bpy.app.handlers.save_post.append(infinite_backups_save_handler)

def register():
    # note: we use save_post so that the backup filename matches the
    # actual saved filename if it was a "save as" event.
    bpy.app.handlers.save_post.append(infinite_backups_save_handler)


def unregister():
    bpy.app.handlers.save_post.remove(infinite_backups_save_handler)

This add-on makes an automatic timestamped backup whenever you save in Blender. Unlike the built-in backup system, this will never delete any old backups.

There is no GUI or configuration. Just enable the add-on and then save as usual. Backups will be created in the same directory.

P.S. No warranty if this destroys your files. The code is only a few lines so please read them and ensure they do what you expect.