What Together AI's $800M Round Says About Elixir

TL;DR: Together AI closed an $800M Series C at an $8.3B valuation on July 1, 2026 — led by Aramco Ventures, with NVIDIA and General Catalyst participating, and annualized bookings past $1.15B last quarter. Here’s the receipt that doesn’t make the funding headlines: Together AI’s own engineering job postings describe Elixir/Phoenix services on the BEAM running authentication, SSO, OAuth, organizations, projects, API keys, and role-based access control — the layer every other product call in the company routes through. Elixir’s raw usage share is still low single digits. The signal isn’t the share. It’s where a company at this valuation chose to put its critical path, and that it’s hiring publicly to defend the choice.

The round

On July 1, 2026, Together AI announced an $800 million Series C at an $8.3 billion post-money valuation — more than double the $3.3 billion mark from its Series B in early 2025. Aramco Ventures led the round; TechCrunch’s coverage lists Vista Equity Partners, General Catalyst, Emergence Capital, and NVIDIA among the participants, notes the prior $3.3 billion Series B mark, and reports annualized bookings past $1.15 billion in the company’s most recent quarter — on the back of enterprises moving inference workloads off closed frontier models and onto the open models Together AI serves at a fraction of the cost.

None of that is an Elixir story on its face. Together AI is a GPU-cloud-and-inference company; its headline product is compute, not a web framework. But funding announcements and cap tables don’t tell you what’s actually running in production, and the interesting part of this story isn’t in the press release — it’s in the job board.

The receipt: what’s actually on the BEAM

Together AI’s Greenhouse listing for a Software Engineer role on its Identity & Collaboration team — part of the Product Foundations engineering group — spells out the stack in plain language: “Build and ship features across the stack — TypeScript/Next.js on the frontend and Elixir/Phoenix services on the backend.” The scope of that backend isn’t a side project. It’s “authentication flows (including SSO and OAuth), organizations, projects, API keys, and role-based access controls,” and engineers on the team are expected to “learn the Elixir/Erlang VM (BEAM) and how we run it in production.”

Read that list again and notice what it isn’t. It isn’t a marketing site, a docs portal, or an internal admin tool — the places a startup tends to park a language nobody wants to bet the company on. It’s identity and access control: the layer that authenticates every request, scopes every API key, and enforces every permission check across the product. If that layer goes down or gets the concurrency model wrong, nothing else in the platform works correctly either. Together AI put that on Elixir and Phoenix, running on the BEAM, and is hiring engineers into it by name.

I’ve made the architecture case for exactly this kind of choice before — why Elixir fits the AI startup backend covers the concurrency and supervision reasoning in full, and I won’t re-run it here. What’s worth sitting with instead is what it means when a company at an $8.3 billion valuation, closing a $800 million round, is the one making that choice publicly.

Why raw adoption share still says “niche” — and why that’s the wrong number to read

Here’s the concession, stated plainly instead of buried: by raw usage, Elixir is not mainstream. In the 2025 Stack Overflow Developer Survey, Elixir sits at 2.7% of all respondents — low single digits, well behind JavaScript, Python, and the other top-line languages. If you’re grading “has Elixir gone mainstream” as a flat yes/no against that number, the honest answer is no, and anyone telling you otherwise is selling something.

But raw adoption share answers the wrong question for this story. It tells you how many developers, in aggregate, across every kind of company and every kind of workload, happen to write Elixir day to day. It says nothing about where the growth is concentrating, or who is choosing it for the parts of their system that can’t afford to be wrong. Those are different questions, and the second one is the one funded AI infrastructure companies are answering with their hiring budgets right now.

Adoption share is a lagging, backward-looking average across the entire industry, most of which isn’t building anything like what Together AI is building. It smooths a real signal into noise. The signal that actually matters for anyone deciding what to build a new AI-infrastructure backend in isn’t “what percentage of all developers use this,” it’s “what are the best-capitalized, fastest-growing companies in the category choosing for the part of the system every request has to pass through.” Together AI answering that with Elixir, in public, on a job board, the same month it closes a nine-figure round, is a stronger data point for that narrower question than the aggregate percentage will ever be.

It’s not an isolated one, either. Elixir’s flagship web framework, Phoenix, was the most admired web framework in Stack Overflow’s 2023 survey — more developers who had shipped on it wanted to keep using it than for React, Node.js, or Next.js — a satisfaction signal from the people who’ve actually run it, which is a very different thing from a popularity count of people who haven’t. Small usage share and high admiration from the people who use it in production is a specific pattern: a technology that isn’t losing engineers who try it, it’s losing at the top of the funnel, before anyone’s actually run it. Together AI’s hire is what it looks like when a well-funded team gets past that top of the funnel and puts it on the critical path anyway.

One data point — but the right kind

This isn’t a “companies using Elixir” listicle, and I’d be doing you a disservice if I dressed it up as one — a list of logos proves nothing on its own. What’s worth tracking instead is the pattern this round is one data point in: funded AI-infrastructure companies reaching for the BEAM specifically for the stateful, concurrent, always-on layer — identity, access control, collaboration, the connective tissue every other service depends on — while building the rest of their stack in whatever language fits the rest of their stack. It’s the same reasoning behind why the BEAM keeps turning up under AI agent workloads: the parts of a system that have to hold state, stay up, and coordinate concurrent work reliably are exactly the parts where the BEAM’s guarantees stop being a nice-to-have. That’s not “Elixir is eating the world.” It’s “Elixir is winning a specific, high-stakes layer of infrastructure at companies with the capital and the technical judgment to choose deliberately,” and that’s a narrower, more useful claim to make than the flat mainstream-adoption one, because it’s the claim the evidence actually supports.

If you’re already building on Elixir and want the durable-execution side of this argument rather than the identity-layer side, I’ve covered that separately: running AI agent jobs on Oban instead of a bespoke queue is the same BEAM guarantees applied to a different critical path.

If you’re weighing the same choice for an AI startup’s backend — what belongs on the BEAM, what doesn’t, and where the concurrency model actually earns its keep instead of just sounding good in a pitch — that’s the conversation I have with founders and CTOs in fractional CTO and engineering leadership engagements. Bring the actual system you’re building; the right answer depends on what’s in it, not on a job posting from a company that isn’t yours.