According to v2, this is the new format

https://api.stackexchange.com/docs/tags#page=1&pagesize=100&order=desc&sort=popular&filter=default&site=stackoverflow&run=true

https://api.stackexchange.com/docs/tags#page=2&pagesize=100&order=desc&sort=popular&filter=default&site=stackoverflow&run=true

....

Update:
Version 1 of the API is long shut down. Here's sample paging on API version 2:

• /2.2/tags?page=1&pagesize=100&order=desc&sort=popular&site=stackoverflow
• /2.2/tags?page=2&pagesize=100&order=desc&sort=popular&site=stackoverflow
• etc...

Obsolete, version 1 answer:

http://api.stackoverflow.com/1.1/tags?pagesize=100&page=1

http://api.stackoverflow.com/1.1/tags?pagesize=100&page=2

etc...

Not like this?

http://api.stackoverflow.com/1.1/tags?pagesize=100&page=1

http://api.stackoverflow.com/1.1/tags?pagesize=100&page=2

....

According to v2, this is the new format

https://api.stackexchange.com/docs/tags#page=1&pagesize=100&order=desc&sort=popular&filter=default&site=stackoverflow&run=true

https://api.stackexchange.com/docs/tags#page=2&pagesize=100&order=desc&sort=popular&filter=default&site=stackoverflow&run=true

....