Rayon announced a €10 million Series A on its own blog on 23 September 2026, with trade coverage following on 29 September. The round is led by Partech, with existing backers Northzone, Foundamental and Seedcamp participating. Partech and the trade coverage put Rayon’s total funding at close to €16 million; the company’s own post gives no cumulative figure.
Rayon sells a computer-aided design application that runs in a web browser. Its users are interior designers, architects and space planners, and what it sets itself against is the desktop CAD licence. The company says more than four million drawings have been created in the software and that its team now numbers 35. It was founded in 2021 by Bastien Dolla, co-founder and chief executive, and Stanislas Chaillou, co-founder, COO and CPO.
Partech’s note also sets out what came before: a €4 million seed in September 2023 co-led by Northzone and Foundamental, and a €1.7 million pre-seed in 2022 led by Seedcamp. Partech adds that the team has tripled in size.
Neither the announcement nor the trade coverage gives a valuation, and a search for a reported figure did not surface one.
The Product Being Funded Has Not Shipped Yet
The capital is attached to a specific and dated piece of roadmap, which makes this round easier to read than most Series As.
Rayon’s application today is a 2D tool. Its public site markets plans, floor layouts and drafting, along with a set of AI features: asset generation and search, a question-answering assistant, image generation for concept visuals, and a tracing tool that converts an image into vector linework. Nothing on that page markets 3D, and both the company and its lead investor place 3D in the forthcoming release rather than the current one.
Version 4, which AEC Magazine reports is due later this year, is where both halves of the announcement land. It brings 3D into the collaborative environment, and it brings a broader set of AI capabilities into the app — generative tools, AI-assisted workflows, and agentic AI that can carry out tasks within a project. In other words, the round funds a version of the product that has not shipped, on a timeline measured in weeks rather than years.
Chaillou, quoted by tech.eu: “Interior design needs its own approach to AI, not a borrowed one. We’re building ours directly into the drawing experience, while staying connected to the AI tools designers already use.”
That last clause is the one worth noticing. It concedes that designers are already using general-purpose AI tools and declines to compete with them head-on.
Why “In the Drawing” Is a Real Position and Not a Slogan
This is analysis, and should be read as such. But the distinction Chaillou is drawing has a technical basis, and it is the most interesting thing in the announcement.
Most AI that has reached architecture and interior design in the last three years attaches to the image. You describe a room, or feed in a rough massing, and a model returns a picture. These tools are genuinely useful for concept work and genuinely useless downstream, because a picture has no dimensions, no layers, no schedule and no specification attached. Nothing in it can be built from, and nothing in it survives contact with a contractor. The output is a mood, not a document.
A drawing is the opposite. It is a structured artefact: geometry with real dimensions, objects that carry properties, layers that mean something, and — in Rayon’s case — plans, styling and schedules held in one shared workspace. An agent operating on a drawing can do work whose results are checkable, because the drawing is the thing the rest of the project consumes. An agent operating on a render can only produce another render.
Whether Rayon executes on that is unknown, and V4 has not shipped. But the choice of surface is not arbitrary, and the company has an unusual reason to have made it deliberately. Chaillou is an architect by training — a Harvard Graduate School of Design MArch ‘19 — and he turned his research on AI in architecture into Artificial Intelligence and Architecture, From Research to Practice (Birkhäuser, 2022; revised and expanded second edition 2025). Partech’s note says he has spent close to a decade researching and writing about AI in architecture. The research behind the argument predates the company.
The Market Being Entered
Dolla, quoted by tech.eu, on what the company hears in sales meetings: “The most common thing we hear in a demo is surprise. People open Rayon in a browser and expect a toy web application, but they discover a performance and a feature set that are better than most legacy CAD software.”
Partech’s own note names Virgin Atlantic, CityHub, Coloc Housing, Nolt Mathis and Morning among Rayon’s users, and reports monthly savings figures from two of them — €10,000 a month at CityHub and €11,000 a month at Coloc Housing. Those are customer-reported numbers relayed by the lead investor, and are presented here as such. Réza Malekzadeh, a general partner at Partech, in the same note: “Interior design has been underserved by software for decades, and Rayon is the first team we’ve seen build the design layer this space actually needed…”
Rayon sits at the smaller end of a category this newsroom has been tracking all year, where the through-line is documentation rather than imagery. Illoca raised $13 million on an AI canvas that turns an architect’s sketch into documentation. Motif shipped an agent-native BIM authoring tool and priced it per AI user rather than per seat. Endra took $50 million from a16z into the most rule-bound corner of building design. Each is attacking a different document, and each has concluded that the document, not the picture, is where the value is.
Rayon’s version of that bet is aimed at a different room in the building — interior layouts for hotels, restaurants, offices and airport lounges, per its own announcement, rather than structural or MEP coordination. And its delivery model is part of the pitch: a CAD tool that opens in a browser tab is a distribution argument as much as a technical one, which is what Dolla’s remark about demo surprise is really about.
The thing to watch is not the round. It is whether V4 arrives before the end of the year, and whether the agentic features in it operate on the geometry or merely alongside it.
