Slack unveils a new design with an updated navigation bar, collapsible sections within the sidebar, improved ways to respond to threads and mentions, and more
It arrives today, and it's more customizable and simplified — Slack is unveiling a big redesign to its communications app …
Context & Ripple Effects
This 2020 redesign is one stop in Slack's long-running effort to tame its own interface: after debuting threaded messages in 2017 to attach side-conversations to specific messages, and previewing email replies and calendar integrations in 2019, Slack is now restructuring navigation itself — an updated top bar, collapsible sidebar sections, and faster thread-and-mention replies.
It matters because the direction set here compounds: three years later Slack shipped what it called its biggest redesign yet, adding a Home section, a left sidebar, a Teams-style DMs section, and a unified Activity inbox — evidence that the 2020 changes were early steps toward a more structured, inbox-like workspace rather than a one-off polish.
First-order effects
- Heavy Slack users immediately get a calmer interface — collapsible sidebar sections let them group channels and cut visual noise, while improved thread and mention responses shorten the path to clearing notifications.
- Power users who had memorized the old navigation face a relearning cost on day one, making customizability the design's key defense against churn among its most invested customers.
Second-order effects
- The redesign keeps Slack structurally competitive with Microsoft Teams, whose layout Slack would later explicitly borrow from in its 2023 DMs section — each redesign narrows the differentiation gap and pushes competition toward features and pricing instead of interface familiarity.
- A more structured conversation surface sets up Slack's later monetization moves, like paid project-management features such as Slack Lists, which depend on organized channels and threads to be usable.
Third-order effects
- If the cadence holds — incremental restructuring in 2020, a ground-up rebuild by 2023 — workplace chat apps converge on the same inbox-plus-sidebar architecture, competing less on layout and more on what runs inside it, including the AI agents Slack now sells through Agents for Slack.
- Repeated large-scale redesigns of a mature product signal that the chat client is becoming a platform surface whose information architecture must keep absorbing new job-to-be-done categories — tasks, activity feeds, agent interactions — rather than remaining a message stream.
The trend: Workplace chat interfaces are steadily converging from free-form message streams into structured, inbox-like work surfaces, with Slack's periodic redesigns tracking that shift.