When comparing IMO vs Keybase, the Slant community recommends Keybase for most people. In the question“What is the best team chat software?” Keybase is ranked 15th while IMO is ranked 20th. The most important reason people chose Keybase is:
Completely end-to-end encrypted.
Ranked in these QuestionsQuestion Ranking
Pro Video call support
Pro Beautiful User Interface
Although IMO has a comparable, and in some cases superior, feature set when compared to the competition its key selling point is its interface.
From LifeHacker when it won "Best IM Client":
Signing on, navigating chats by tapping the tabs at the bottom, searching for buddies, and virtually any other operation is easy to find and use. The app, itself, is very quick. Even sending a voice IM, if you don't feel like typing, is responsive and sends quickly. Everything imo does it does well, but it's excellent navigation really makes it top notch.
IMO also has a fully functional website that you can use for chat while on your desktop or laptop. This really puts IMO ahead of the competition as you can use the same system on all your devices so you don't have to deal with overlapping notifications etc. (Note: IM+ also has this feature)
It should also be noted that it has the highest rating in the App Store due to both the UI and its stability.
Pro Easy to switch between conversations with tabs
Tabbed chats make it easy to switch between conversations
Pro Lists and chat histories are searchable
Both your buddy lists and chat histories are searchable.
Pro Accounts can be linked so you don't have to sign in to several accounts
Pro Push notifications
Pro Concurrent sessions
Concurrent sessions allow you to be logged in on your desktop while also being logged in on your phone.
Pro Chat groups
Pro E2E encrypted
Completely end-to-end encrypted.
Pro Identity verification
Users can publish proofs of identity (PGP public key, Twitter, Facebook, etc).
Free (as in beer) and Open Source Software.
Pro Encrypted file sharing
Securely share files.
Pro Public encrypted filesystem
For sharing files publicly.
Pro 250GB of free team file storage
250GB of free storage for encrypted files in a team.
Pro Public teams
Teams can be public with open access or admin-approved access. Opt-in to list public teams.
Pro Private teams
Teams can be completely private (access granted via admin-approval only, not publicly listed).
Pro Encrypted Git
Encrypted private or team Git repositories with automatic commit signatures.
Pro Blockchain technology
Based on blockchain technology.
Pro Sigchain verification
View/verify the cryptographic signature history of any user.
Pro PGP/GPG support
Encrypt/decrypt any PGP message or file with minimal effort.
Pro Public key encryption
Supports public key encryption.
Pro Private encrypted filesystem
Securely store personal files that only you can access.
Pro Shared private encrypted filesystem
Share files securely and privately with other users, a group of users, or a team.
Pro 250GB of free private file storage
250GB of free storage for privately-encrypted files.
Pro Free static site hosting
Host a public static website for free. Sites are automatically viewable via keybase.pub if an index.html or index.md exist in your public files.
Pro Emoji reactions to limit excessive posts and notifications
Pro E2E encrypted team chat
Teams are E2E encrypted, unlike Slack and other services.
Con No support for third-party instant messaging networks
On March 3, 2014, IMO will start discontinuing support for all third-party instant messaging networks.