Ably, a Pub/Sub messaging platform for devs to bring real time features in their products, raises $70M Series B co-led by Insight Partners and Dawn Capital
Context & Ripple Effects
Ably's $70M Series B lands it squarely into a race that PubNub has been running longer: PubNub took a $23M Series D back in 2019 to power data streams for real-time apps and IoT devices, then followed with a $65M Series E just four months after this round. Both now sell essentially the same thing — messaging, presence, and data-stream APIs that let developers ship live features without building infrastructure.
The round also fits the broader 2021 pattern of investors funding single-feature API layers: Stream raised a $38M Series B for embeddable chat and activity streams, and Daily raised a $40M Series B for video and audio APIs. For Insight Partners, this is a repeat bet on the category — the same firm later led Appsmith's $41M low-code Series B.
First-order effects
- Ably gets the balance sheet to compete head-on with PubNub's freshly capitalized Series E, turning what was an incumbent-vs-challenger gap into a two-horse contest for developer mindshare in Pub/Sub messaging.
- Insight Partners and Dawn Capital double their exposure to API-first developer infrastructure, with Insight now backing two separate dev-tools platforms (Ably and Appsmith) on similar theses.
Second-order effects
- Adjacent API vendors like Stream (chat/activity feeds) and Daily (video/audio) face the same buyer evaluating which real-time primitives to buy versus build, pushing each toward broader feature bundles to stay in the procurement conversation.
- Pricing pressure builds at the infrastructure layer: with two heavily funded Pub/Sub players competing for the same engineering teams, per-message or per-connection economics become the differentiator rather than raw feature checklists.
Third-order effects
- If the funding cadence holds, real-time functionality consolidates into a small set of rented API layers — chat, presence, streaming, media — mirroring how payments and auth were abstracted away from app developers, and raising switching costs once products are wired to one provider.
- For investors, Insight's pattern across Ably, Appsmith, and later its reported Wiz exit suggests a durable strategy of concentrating capital in developer-platform categories where usage scales with customer product adoption.
The trend: Venture capital is systematically funding API-first infrastructure startups that let developers rent individual product capabilities — real-time messaging among them — rather than build them in-house.