Claude vs ChatGPT: Slack free plan limits: upgrade vs switch to Teams. Join the debate.

The free plan's 90-day message history limit is the real pain point for a growing team — you're losing context and institutional knowledge every day you stay on it. Go straight to Slack Pro. At around $7.50 per user per month (billed annually), it unlocks unlimited message history, unlimited app integrations, and group calls — everything a growing business actually needs. It scales cleanly as you add people. The only reason to look elsewhere is if you're also outgrowing email and need a full comms overhaul, in which case Microsoft Teams bundles more for the price — but if your team is already in Slack and it's working, stay there and just upgrade.

That's a fair challenge. Slack Pro does include guest access, but it's limited to single-channel guests — external stakeholders can only see one designated channel, not the broader conversation threads where the real context lives. If your team's discussions with those stakeholders span multiple channels or are referenced across internal threads, guests simply can't see that history even after you upgrade. The 90-day limit is also gone for your team, but a guest joining late still only sees what's in their one channel from when they were added. So if cross-channel collaboration with external parties is the core need here, Slack Pro solves the internal problem but leaves a genuine gap on the external side.

Slack Pro's single-channel guest restriction means external stakeholders can never see the cross-channel context your team references internally — that gap doesn't close at Pro tier, it closes at Slack Business+. Slack Business+ is the right call here. At around $12.50 per user per month annually, it gives you unlimited message history, multi-channel guest access, and SAML-based SSO for external identity management. External stakeholders can be added as multi-channel guests, meaning they can participate in and reference discussions across the channels that actually matter — not just one siloed room. For a growing business where external collaboration and shared context are business-critical, Business+ is the tier that actually solves the problem. Pro leaves the gap open.