What seemed like some minor changes to the Terms and Conditions for Slack users may have serious repercussions for marketers

Made late last month, the Slack API (application programming interface) changes will prevent third-party applications from bulk accessing or storing chat data from the platform. Commentators cite the company’s wish to restrict the use of Slack message data to train large language models (LLMs).

Apps not officially listed in the Slack Marketplace will also be subject to one API requests per minute, under the new Terms.

Third-party analysis apps on which many organisations rely, such as brand sentiment analysis software, or search engines deployed to find specific keywords among chats, could no longer function as effectively, with significant negative impact on marketing operations.

Additionally, any applications used to trigger automated marketing workflows as a result of activity in Slack (such as alerting teams to trending keywords inside Slack messages, for example) might also experience a massive slowdown and drop in effectiveness. This could alter the way in which teams react in real-time to emerging sentiment or trends in companies using Slack.

Companies using APIs in apps that produce summaries of team output will begin to notice restrictions, and training of internal AI assistants using data from Slack will have to cease – unless those applications are officially approved by Slack and appear in the Slack Marketplace.

Note that these strictures apply to third-party applications that companies source from outside the Slack Marketplace. Companies that have already built their own internal tools using the Slack APIs for marketing purposes are not subject to changed terms. Additionally, Slack is currently working on methods that will allow its paying users access to the centrally-stored data storage run by Slack, rather than having to send API requests to pull data to a local store – thus creating a copy (or silo) of the contents of chat messages and replies. On-going progress on that project can be seen here.

The revised Terms & Conditions are described in a blog on the Slack developers’ website as follows: “Applications published in the Slack Marketplace and existing internal customer-built apps created before May 29th, 2025 will keep their current, higher rate limits. Customers building custom applications for internal use have no restrictions on accessing their Slack data, as has always been the case. “

Companies offering services to marketing departments using applications outside of the Slack Marketplace will be most affected by the recent changes. Those apps will only be able to access the Slack Web API only once per minute, and request only 15 messages per call.

Which way now?

Salesforce acquired the enterprise chat and messaging application in July 2021, in a move at the time tha was seen as an attempt to consolidate the core CRM functions in Salesforce with in-house and customer-facing communications, courtesy of Slack. By developing a unified enterprise-wide platform, Salesforce sought to provide its customers with a seamless environment that combined collaboration with business data, automated processes, operational simplification, and a single-source-of-truth platform for organisations.

However, the creation of a so-called walled-garden comes with the proviso that participants have to adhere by the rules, and the costs of such a platform. Marketers reliant on Slack message analysis and action thereon may wish to consider migration to Slack-approved tools to ensure long-term workflows. Arguably, doing so would comes with benefits from deeper integration with the rest of the Salesforce technology portfolio. For instance, many will be aware of Salesforce’s Agents (AKA Agentforce), one of the first widely-available and most powerful agentic AIs which can take actions on a Salesforce user’s behalf.

To remain compliant with Slack’s new Ts&Cs, companies should be particularly wary of any tools they might currently be using which leverage AI on Slack message data – something that seems to be at the heart of the rules changes. Furthermore, any workflows dependent on third-party applications’ access to Slack will need to be replaced with sanctioned alternatives.

(Image source: “Hoover Dam overlook” by Creativity+ Timothy K Hamilton is licensed under CC BY-NC-ND 2.0.)

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