Stride (previously HipChat) vs Keybase

You can access HipChat from pretty much every common platform. HipChat even allows chatting via SMS.

You can ping people to get their attention even if they are not online by @mentioning them. Depending on how the person has set their account up it can be by notifications via in-app sounds, visual alerts, and even email, SMS, or mobile app push notifications.

Including Asana, Github, Zendesk, WordPress, MongoDB, TeamCity, JIRA, Confluence, PowerShell and more that 40 others.

Free with unlimited users, $2/user/month for voice + video calls, screencasts, full history retention and management. (Even enterprise feature like SAML)

An intuitive, easy to overview interface listing both online and offline users.

Things like photos get automatically embedded in the chat thread once you upload them.

You can invite people to join conversations even if they don't have a HipChat account. HipChat will generate a link to share and the guest will only need to enter their name to join the conversation.

HipChat has an optional desktop client powered by Adobe AIR.

HipChat audio and video works on mobile platforms and web browsers.

Participate and keep tabs on ongoing discussions on particular topics or amongst certain groups of people.

If you are worried about third-parties getting access to your data you should consider self-hosting. With self-hosting you are in control over where your data is stored, who has access to it. You will also not be vulnerable to exploits of a third-party provider.

Pasted code can be colored based on syntax.

A big company with experience will bring in more options like Google Apps One Time Login.

E.g. part, away, all, here etc.

Completely end-to-end encrypted.

Users can publish proofs of identity (PGP public key, Twitter, Facebook, etc).

Free (as in beer) and Open Source Software.

Securely share files.

For sharing files publicly.

250GB of free storage for encrypted files in a team.

Teams can be public with open access or admin-approved access. Opt-in to list public teams.

Teams can be completely private (access granted via admin-approval only, not publicly listed).

Encrypted private or team Git repositories with automatic commit signatures.

Based on blockchain technology.

View/verify the cryptographic signature history of any user.

Encrypt/decrypt any PGP message or file with minimal effort.

Supports public key encryption.

Securely store personal files that only you can access.

Share files securely and privately with other users, a group of users, or a team.

250GB of free storage for privately-encrypted files.

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.

Teams are E2E encrypted, unlike Slack and other services.