Redirects for migrations and renames
When a URL changes, a permanent (301 or 308) redirect sends visitors and search engines to the new one and carries its ranking signals over. Map every old URL that has traffic or links to its closest new page, not all to the home page.
Rules are generated with paths only when old and new are on the same site, and with full URLs when they move to another domain.
Questions
301 or 308?
Both are permanent. 308 keeps the request method; for pages, they behave the same in search.
How many redirects can I add?
As many as you paste. Very large maps are better served from a lookup table than thousands of rules.
How long should I keep redirects?
At least a year, and ideally for good if the old URLs have links.
Is anything uploaded?
No. Rules are built in your browser.