If you run a shared Slack channel with your customers — a Connect channel, a support workspace, a community — you are sitting on a stream of testimonials that no one is capturing. Somewhere in the scrollback, a customer typed "honestly this saved us the whole quarter, we were about to build it ourselves" and then moved on to their next question. Nobody screenshotted it. Nobody asked if they could use it. It scrolled up and out of view, and a week later it's effectively gone. That message was more credible than anything you could have solicited, and you let it evaporate.
The reason it's more credible is the reason it's hard to capture: it was never meant for you to publish. It was a working comment, typed fast, in the flow of getting something done. That is exactly what makes it believable to a prospect. A solicited testimonial reads like it was written for a website. A Slack message reads like a real person talking to another real person, because that's what it was.
What a usable Slack testimonial actually looks like
Not every nice message is a testimonial. "Thanks, that worked!" is gratitude, not proof — it says nothing a prospect can use. The messages worth capturing share three traits. They're specific: they name what changed, ideally with a number or a before-and-after. They're attributable: they came from a real person at a real company whose name would mean something to your buyers. And they're unprompted: the customer volunteered them, which is the whole source of their power.
"This saved us the quarter" is close, but on its own it's still vague. The best ones go further: "we cut our onboarding time from three weeks to four days after switching." That is a testimonial. When you see one go by, the instinct to act on it should be immediate, because the window is short.
Capture it in the moment, verbatim
The first job is preservation, and it's more delicate over Slack than it looks. Screenshot the message — but screenshot it honestly. The one thing that will destroy trust faster than having no testimonials is a doctored one, and Slack screenshots are unusually easy to fake and unusually easy to catch faking. Capture the real message, with the real name and avatar, without editing the words. If you need to trim surrounding messages for privacy, that's fine, but never alter what the customer actually said. Attributing words to a named person that they didn't quite type is the kind of shortcut that turns a proof asset into a liability the first time that person sees it.
If the message contains anything sensitive — internal metrics, a competitor's name, a colleague's complaint — note that now, because it will shape what you're allowed to ask for later.
Ask in the same channel, the same day
The mistake most teams make is waiting. They see the message, think "we should use that," and file it away to deal with later. By the time they circle back, the moment has cooled and the ask feels transactional. Reply in the thread while the feeling is still fresh: "This genuinely made our day — would you be open to us using it as a customer quote on our site? Totally fine either way, and we'd link it back to you / your company however you prefer."
Asking in the same channel does two things. It keeps the request casual and low-stakes, matching the register of the original message. And it makes consent easy — the customer can say yes with a thumbs-up react and one line, instead of a formal email exchange. The lower the friction, the more yeses you get.
Get consent on the record, not just a thumbs-up
A react is a signal, not a permission. Before you publish, you want an unambiguous yes and clarity on attribution: full name and company, first name and company, first name only, or anonymous by role ("a VP of Engineering at a Series B fintech"). Confirm the exact wording you'll use, especially if you're trimming the message for length — send them the final quote as it will appear and let them approve it. This is not bureaucracy; it's the step that means the testimonial can never blow up on you. A customer who approved the exact words will defend them. A customer who's surprised to see themselves quoted will ask you to take it down, usually at the worst possible moment.
If the message named metrics or internal details, this is also where you confirm those are okay to publish. Sometimes the customer is happy to be quoted but wants the specific number softened. That's an easy edit to make now and an ugly one to make after it's live.
Turn one message into a repeatable habit
The teams that get the most out of Slack testimonials don't treat each one as a lucky find. They build a lightweight habit: a saved-items list or a single internal channel where anyone who spots a quotable message drops the link. Once a week, someone reviews the list, asks for consent on the strong ones, and publishes. The channel is already producing this content daily — the only variable is whether you catch it before it scrolls away.
The broader point is that your customers are describing your value in their own words constantly, in every channel they talk to you through. A message in Slack is just one of those channels, and it happens to be one where people are unusually candid. Capture it honestly, ask for it kindly, confirm consent cleanly, and you turn a stream you were ignoring into a steady supply of the most believable proof there is.