The 90-day wall

Slack’s free plan is generous in every way except the one that matters. You get unlimited users and channels, but only 90 days of message history.

Your older messages are not deleted. They are held, and you cannot read them until you pay. For a team that has been on the free plan for two years, that is a decision about the archive as much as about the software, and it is the moment most people start searching.

Pro is $8.75 per user a month, Business+ $18. For thirty people on Pro that is $3,150 a year, largely to read your own history.

Pumble’s free plan keeps all of it, for an unlimited number of users, at no cost. Whether the rest of Pumble suits you is a separate question, but on that specific point the comparison is not close.

Slack alternatives compared

Cheapest paid tier and what the free tier really allows, checked against each vendor’s own page on 6 September 2026.

Self-hosting is the real differentiator

Three of the tools here run on your own server, and that changes the nature of the purchase.

Search “Slack alternatives” and the related searches include open source, self-hosted and Europe. Those are the same question asked three ways: who can read our messages, and under whose jurisdiction?

Mattermost is the mature answer for organisations with an IT function. Rocket.Chat does the same and adds customer conversations. Element is a client for Matrix, an open protocol, which means two organisations running separate servers can still message each other, and several European public bodies have adopted it for that reason.

The cost is not zero. Someone runs the upgrades, the backups and the on-call. Weigh that against the per-seat bill honestly, and remember that a chat outage is a work stoppage.

Migrating without losing the archive

Export first, and check what you get.

Slack’s standard export covers public channels: messages and metadata as JSON files. Private channels and direct messages require a higher plan and, usually, an approved compliance request. Do not assume DMs come with you.

Mattermost, Rocket.Chat and Pumble all import Slack exports with varying fidelity. Threads and reactions usually survive. Custom emoji, workflows and app integrations do not.

Practical sequence: export, verify the export opens, stand up the new tool alongside Slack for two weeks, move one team first, then the rest. Keep Slack read-only for a month.

Does anyone still use Slack?

Yes, and that is a fair thing to weigh. Its advantage is not features, it is that your contractors, clients and partners are already on it, and Connect channels make cross-company work easy.

That network effect is the strongest argument for staying and the weakest reason to choose it fresh. If your usage is internal, it counts for nothing. If half your work happens in shared channels with other companies, it counts for a great deal, and the cheaper tools will not replace it.

How we test and price these tools

Every price here was read from the vendor’s own pricing page in a browser on 6 September 2026, not copied from another round-up.

For team chat we treat message history as the headline feature, not a footnote, because it is the limit teams actually hit. We record what each free tier caps: history, users, apps or calls. For self-hosted tools we state whether the free edition is the full product or a cut-down community version.

We read current Reddit threads for each tool, so the picks reflect what teams are moving to this year. No vendor pays for a place on this list.