Kalshi Live Chat Scales 14x with Stream Chat and AI Moderation
A Lean Team Wagering on Social
Kalshi's leadership made a bet. In a category where every competitor offers similar contracts, the real edge would be community. Engaged traders talk more, trade more, and bring in the next trader. Group chats tied to every live market, community groups, and influencer-led discussions were the mechanism for that thesis.
Their perpetual futures product launch in June 2026 also created a new, high-engagement use case for live chat. Perps trade continuously, with prices moving in real time instead of settling on a single date, giving traders more reason to talk through what they're seeing.
To execute on it, Kalshi needed chat infrastructure that could support real scale. Their Stream integration ran lean, with one engineer owning the entire chat build. Stream built additional features specific to Kalshi's live-event experience, including a "Live Switcher" that sorts channels by viewership, so the busiest markets surface automatically during a big game.
Once launched, engagement multiplied.
In just four months, monthly engaged chat users grew 650%, messages sent per month climbed 1,330%, and text moderation checks grew 1,160%.
In tandem, three of the year's biggest live sporting events (the NBA Finals, the FIFA World Cup, and the NFL opening weeks) tested the chat and moderation infrastructure at scale.
Results: Three Live Events
Stream's infrastructure, built for <40ms latency, stayed stable as usage peaked through three global sporting events in 2026.
NBA Finals
The Knicks' five-game series win over the Spurs landed within Kalshi's steepest month-over-month jump.
FIFA World Cup
The World Cup carried Kalshi's chat growth and trading numbers to another peak.
NFL Opening Weeks
Ahead of NFL season, Kalshi opened chat to every market simultaneously for the first time. Before the month's end, growth spiked again.
Moderation Built for a Trading Floor
Stream's flexible moderation platform allowed Kalshi to create custom policies tailored to prediction markets.
Kalshi's moderation is built around the specific ways people try to abuse a market conversation: coordinated attempts to move a price with fake insider claims, pump-and-dump-style pressure campaigns, and traders trying to pull others into private Discord or Telegram groups to sell "signals" off-platform.
It also watches for scam patterns unique to money changing hands in chat (a "guaranteed win" pitch followed by a request to send funds to a Venmo or CashApp handle, for instance) on top of the harassment and spam coverage any chat product needs.
Scaling Without Breaking
Kalshi's traffic (its Go backend and Flutter client alike) lands in a single rate-limit bucket per endpoint, so there's no hidden slack to fall back on if traffic on one endpoint spikes. On the heaviest day in a recent capacity review, one endpoint hit 9,150 requests a minute against a 10,000-per-minute ceiling, a 91.5% peak. Across roughly 49 million requests that week, zero were throttled.
The endpoint that actually carries chat messages, SendMessage, was running at just 23.5% of its own cap at the same time. In other words, the spike came from connection and presence traffic during a reconnect surge around a big match. It didn't come from chat itself buckling under message volume.
Stream also moved Kalshi onto dedicated infrastructure ahead of the NFL season to prepare for additional traffic spikes.
| Endpoint | Limit / min | Peak / min | Utilization |
|---|---|---|---|
| StopWatchingChannel | 10,000 | 9,150 | 91.5% |
| UpdateChannelPartial | 3,000 | 2,338 | 77.9% |
| UpdateUsers | 15,000 | 10,421 | 69.5% |
| SendMessage | 5,000 | 1,175 | 23.5% |
Kalshi Is Still Scaling Market by Market
Monthly trading volume has grown 440%, from $14.8 billion in April 2026 to $80 billion in October 2026. Many factors contributed to that growth, including new markets and major live events. In-app communication scaled with Stream over the same period.
Kalshi built chat around a thesis about how prediction markets grow: get traders talking, keep them trading, and let them bring the next one in. Stream's role is to keep chat fast, stable, and safe as that community grows.