Launch HN: Vendo (YC S26) – Let users build features on top of your product

Hi HN, we’re Yousef & Nour, founders of Vendo ( https://vendo.run ).Vendo lets users create new features inside the software they already use.A user describes the dashboard, workflow, or small app they need, and Vendo builds it on top of the product’s existing data, API, and interface.Demo: https://www.youtube.com/watch?v=VdpHehY64ls We built Vendo because every SaaS eventually faces the same problem: every customer needs something slightly different.One wants a new report and another needs a workflow that only makes sense for their team.These requests either sit on the roadmap, become one-off engineering work, or force the customer into spreadsheets and external tools.

We wanted the user to be able to create the missing feature themselves, without leaving the product.Here is how it works: - npx vendo init reads the product's API surface, theme, routes, and more.These are used so that the apps Vendo creates (1) look on-brand and native and (2) have the ability to read data and perform actions directly through the company's API - When a user asks for a feature, we have a custom Vendo harness that writes a React component with a bunch of Vendo add-ons and guardrails (ex. ability to make calls to the host API + our component library).Every save is compiled, type-checked, run against real API responses, and rendered before the user sees it.

We just released a benchmark and write-up here with more info for anyone interested: https://vendo.run/blog/generating-product-ui-measured - We use QuickJS to make sure that anything the agent creates is sandboxed and can't mess with the company's site.Vendo compiles the component and runs it with Preact inside a QuickJS VM with no access to the DOM, network, or clock.The VM returns a UI tree, which the host renders using the product’s registered components.When the user clicks something, QuickJS emits a tool call;the host executes it through Vendo’s guard and passes the result back into the same VM, preserving the screen’s local state.

There's a lot of generative UI right now: streaming developer-written components into a chat (Vercel AI SDK, CopilotKit, Thesys), or rendering your app inside someone else's assistant (OpenAI Apps SDK, MCP Apps).We differ on two things.Vendo lives in your product and acts through your API as the signed-in user, so what it makes is durable: real apps users keep, pin, and run on triggers while they're away, and not components that are merely confined to a chat.

Plus, it's not capped at putting together a bunch of prebuilt components: the agent can build arbitrary apps, from a quick dashboard out of your own components to real custom code running in a sandbox, and either way data only ever comes from tool calls to your API.Here are some things customers are using Vendo for today: - Letting their users create custom dashboards and reports.These are mainly UI-based and focused on letting the user see the exact graphs and metrics they care about - Letting their customers