Lagrange is used by many and by this point – I assume – other clients are expected to support similar features that can be found in Lagrange.

Features

• Autogenerated page style and Unicode icon for each Gemini domain
• Smart suggestions when typing the URL — search bookmarks, history, identities
• Sidebar for page outline, managing bookmarks and identities, and viewing history
• Multiple tabs and split view
• Identity management — create and use TLS client certificates
• Audio playback: MP3, Ogg Vorbis, WAV
• Scaling page content
• Split View for browsing two pages at once (available on iPadOS on Lagrange)
• Haptic feedback (available on iOS and iPadOS)
• Customizable UI accent color
• Open image and audio links inline
• Find text on the page
• Instant back/forward navigation using cache
• Subscribe to Gemini and Atom feeds
• Search engine intergration
• Support for protocols: Gopher, Finger, Spartan, New, Misfin and Guppy (TODO: add links to those)
• Proxy servers for Gemini, HTTP and Gopher content

TODO: read about:help in full in Lagrange and write more stuff to this milestone