There is one number in Slack's pricing that explains the entire business: 90 days. That is how much message history the free plan retains. Everything else is detail.
The mechanism
A company adopts Slack for free. For three months everything is fine. Then someone searches for the reason a decision was made in March, finds nothing, and discovers that the reason is gone. Not archived — gone.
By that point Slack holds the company's working memory: the reasoning behind decisions, the context around customer problems, the half-explanations that never made it into a document. The upgrade is not to a better chat product, it is to keeping what you already have.
This is one of the most effective conversion mechanics in business software, and it is worth saying plainly that it is a pricing decision rather than a storage constraint.
The tiers
Free — 90 days of history, up to 10 app integrations, one-to-one huddles.
Pro —
$7.25per user per month annually,$8.75monthly. Unlimited history, unlimited apps, group huddles, basic AI.Business+ —
$15annually,$18monthly. Advanced AI: search, daily recaps, workflow generation.Enterprise+ — contact sales. Enterprise search, multiple SAML configurations, information barriers, legal holds.
Credit where it is due: the annual-versus-monthly gap is about 17% on Pro, which is one of the fairer spreads in this whole round-up. Pipedrive's is 71%.
Is Business+ worth double?
Pro to Business+ roughly doubles the seat cost. On a hundred-person company that is about $9,300 a year of additional spend. The difference is largely AI: AI search across the workspace, daily recaps of busy channels, and workflow generation from a natural-language description.
AI search is the one with a real argument behind it. Slack's conventional search has always been mediocre at retrieving a conversation you half-remember, and semantic search over a few years of channels genuinely helps. Whether it helps $7.75 per person per month worth is a question only your own usage answers, and the honest advice is to run Business+ on one department for a quarter and count how often anyone uses it.
Daily recaps are pleasant and inessential. Workflow generation is the same trade as everywhere else in this review: impressive for simple flows, and for anything complicated you end up specifying the logic so precisely that you have written the workflow anyway.
Slack Connect, which is the genuine moat
Shared channels with other organisations are the feature nobody has matched. Working with an agency, a customer or a supplier in a shared channel rather than an email thread is a different working relationship, and it is the single strongest reason to choose Slack over Microsoft Teams if you are not already committed to Microsoft's estate.
The administration around it is less good — guest accounts, multi-channel guests and external members are accounted for in ways that require attention at scale, and the billing implications are easy to get wrong. Assign someone to audit external membership quarterly.
The cost that is not on the invoice
Documentation decay
Slack is so convenient for asking that it removes the incentive to write anything down. Knowledge that should live in a document lives in a thread, and a thread is findable only by someone who already knows it exists.
This is not Slack's fault and it is a real consequence of adopting it. The teams that handle it well have an explicit convention — decisions get written up somewhere durable, and the Slack thread links to the document rather than being the document. The teams that do not end up paying for Business+ AI search to compensate for documentation they never wrote, which is an expensive way to solve a free problem.
Interruption
Worth stating once: default notification settings in a busy workspace are hostile to focused work. This is configurable, most people never configure it, and the productivity cost is larger than the licence.
Verdict
7.6. The product is excellent — the interface quality, the reliability and the app ecosystem are all category-leading, and Slack Connect is unmatched.
The score reflects the pricing posture. Charging for your own history is effective and it is not generous, and doubling the price for AI features whose value is unproven is asking customers to fund a bet. Buy Pro. Trial Business+ on one team before rolling it out, and write your decisions down somewhere other than Slack. Current plans are on Slack's pricing page.
Softmarque is not paid by the products it reviews. Prices and plan names were taken from the vendor’s own pricing page on the date shown above and change often; nothing here is financial, legal or accounting advice.