A 20-person team spread across Singapore, London, and California doesn't have "normal" working hours. Slack's real-time assumption breaks within a week. You need a platform that rewards async-first culture without punishing the person who posts at 11 PM their time and gets drowned in emoji reactions by morning. We tested Slack, Microsoft Teams, Lark, and Orin on the mechanics that actually matter: notification tuning granular enough to let people sleep, message threading that doesn't fragment context, and—critically—the ability to isolate customer conversations from internal team banter so a sales rep can find the deal context without wading through 14 threads about the coffee machine. The async-first gap: Why Slack loses distributed teams Slack's strength is real-time collaboration. That's also its weakness for distributed work. The platform assumes you want to know when someone mentions you, replies in a thread, or reacts to your message—even if "someone" is in Singapore and you're in San Francisco. Out of the box, Slack's notification controls are broad but not precise. You get DMs, mentions, keywords, and threads you've replied to —or you turn off notifications entirely and miss urgent messages. The granularity between "wake me for everything" and "silence me completely" is narrow. For a distributed team, this matters. A developer in London closes their laptop at 5 PM and doesn't want their phone lighting up with 40 unread notifications from the Singapore morning standup. But they do want to see if their code review was blocked. Slack's default setup forces a choice between two extremes. A secondary issue: Slack mixes internal team chat with customer communication. A sales rep using Slack as their inbox sees shared inboxes alongside team channels. Context switching is constant. A customer message appears next to a joke about the quarterly planning session, and suddenly you're explaining to the customer why they saw an inside joke in the shared channel. Teams: Notifications tuned, but fragmented by channel sprawl Microsoft Teams offers more granular notification control than Slack. You can mute specific channels, set quiet hours by timezone, and tell the platform to only notify you for @mentions in certain channels. It's closer to what distributed teams need. The problem is channel sprawl. Teams' folder structure and the ability to create channels for everything means a 20-person team typically ends up with 30+ channels. Threading exists, but it's underused because channels themselves are so easy to create. A sales rep looking for customer context finds a conversation across four channels, a Teams group chat, and an email thread. Integration overhead is also steep. Teams assumes you're buying the entire Microsoft stack (SharePoint, OneDrive, Office 365). If you're using Salesforce, Stripe, or Xero, the connectors exist but require additional setup. For a lean team, that's overhead. Lark: Threading and async-first, but limited integration ecosystem Lark (ByteDance's platform) was built for distributed, multinational teams. It has solid async-first mechanics: strong notification controls, excellent threading, and timezone-aware features that actually work. A message sent at 2 AM doesn't generate a notification—it sits in a digest. Notifications can be set per-channel and per-thread. Do-not-disturb schedules respect local time zones. For a team across three continents, this is the closest thing to actually working defaults. The gap: ecosystem and customer data isolation. Lark's integration library is smaller than Slack's. If you need to pull customer data into a unified view, connect your CRM, or embed customer context in a chat message, the connectors are fewer. And like Slack and Teams, Lark doesn't enforce separation between internal chat and customer communication—that's an architectural choice, not a feature. Orin: Internal chat + customer context in one place (but separate) Orin's approach is different. Team chat is built alongside unified messaging (WhatsApp, SMS, email inbox) and CRM contact and deal context . The architectural choice matters: internal team conversation and customer communication are in separate streams within the same platform. A sales rep receives a WhatsApp message from a prospect. They can see the deal context, the customer's history, and the last three interactions—all without switching to a different tab. They then discuss it in the team chat channel, and that conversation stays separate from the customer message stream. For async work, team chat in Orin uses threading by default, not as an afterthought. A message in a channel that starts a new topic automatically threads. Notifications are tuned for silence by default—you opt into what you want to see, not the reverse. This is built for the distributed case. The trade-off: if you're a Slack-first organization with 50+ integrations already wired to Slack, moving team chat to Orin means choosing between two products or running