How it works
Each letter and digit is swapped for its circled twin: Ⓦⓘⓩⓐⓡⓓ, with circled numbers from ⓪ to ⑨. Tick Bold for white letters in filled black circles, 🅦🅘🅩🅐🅡🅓. Unicode only has filled circles for the 26 capitals, so small letters turn into capitals and numbers stay plain.
Squares too
Squares, next to Bubble, opens the Fancy Text Generator on letters in squares, 🄰🄱, filled when bold, 🅰🅱, with your text carried over. Squares only come in capitals. A few filled squares, such as 🅰 and 🅱, can show up as coloured emoji on some phones.
Questions
Are these the bubble letters people draw?
No. Puffy, outlined poster letters are a drawing or a font file. These are ordinary letters in circles, which is why they paste anywhere as text.
What happens to accents and punctuation?
They stay plain. Only A to Z and 0 to 9 have circled versions. Screen readers read these letters as maths symbols or skip them, and search does not find them, so keep your real name, hashtags and links in plain letters.