- Paris-based Upstream has raised a $3 million pre-seed round with support from Y Combinator, Connect Ventures, and more than 30 founders and operators behind companies such as Framer, Algolia, Asana, Alan, and Webflow.
- The startup is opening to the public after several months in invite-only beta with inboxes designed for both humans and AI agents.
- Founded in 2023 by former Algolia and Doctrine executives, Upstream is betting that AI will do more than just help email users.
Email has withstood every wave of workplace technology, from instant messaging to collaboration platforms to AI assistants. But little has changed in the way people manage their inboxes. Upstream was built by two founders who thought it was impossible to ignore that contradiction.
The Paris-based company has come out of stealth with a $3 million pre-seed round and unveiled to the public what it describes as the first inbox built for humans and AI agents at the same time. The round was backed by Y Combinator, Connect Ventures, and more than 30 founders and operators, including leaders from Framer, Algolia, Asana, Alan, and Webflow.
Built by an executive who expanded a global software company
Upstream was founded in 2023 by Louis Lecat and Jonathan Tiret, a team of seven based at Station F in Paris.
Lecat previously served as Head of Product at Algolia, where he built and led product capabilities and helped grow ARR to over $100 million. Prior to that, he worked on Asana’s product team during a period of high growth and was one of the first 10 employees at AgilOne, which was later acquired by Acquia. Tiret, who served as Vice President of Engineering at legal technology company Doctrine prior to its acquisition, has deep engineering experience and is the creator of Dino Gaïa, one of France’s most popular consumer games in the 2000s.
Together, the founders identified a gap between the way AI agents are beginning to operate in the workplace and the inbox infrastructure that still exists to support them.
“The future of work is not one person and one assistant. It’s teams of people and teams of agents working together. You delegate to an agent, and the agent comes back to you. And it’s across the team. We think it happens in windows, but that’s not where people live. They live in their inboxes. Email wasn’t built for that,” says Louis Lecat.
Why traditional email wasn’t built for AI
Email is still the default communication layer for billions of users around the world, but it is designed to be operated by humans alone. As AI agents increasingly schedule meetings, draft answers, find information, and manage workflows, existing inboxes struggle to support this new way of working.
Upstream’s Inbox allows AI agents to actively manage email by categorizing messages, drafting replies in the user’s style, scheduling meetings, retrieving information, automatically following up, and more. The platform pulls context from calendars, meeting notes, and knowledge bases, and allows users to connect to external AI systems through protocols such as MCP. Thousands of users have already tested the platform in its invite-only beta.
competitive environment
Upstream enters a market that is rapidly being reshaped by both acquisitions and new entrants. Superhuman has long been the most recognized premium email challenger, and although it was acquired by Grammarly in July 2025, it remains a direct and well-resourced competitor. In October 2025, Grammarly rebranded its entire parent company to Superhuman. Superhuman Mail will continue to operate as an active standalone product within a broader AI productivity suite that currently includes writing tools in Grammarly, workspaces in Coda, and a new AI assistant called Superhuman Go. If anything, this acquisition made Superhuman more formidable, not less.
Founded by former Google engineers, Shortwave raised $9 million in 2020 and hasn’t raised publicly since, building an AI-powered email experience centered around automation and intelligent workflows, with annual revenue of $1.9 million and 17 employees as of mid-2025. Fyxer AI is attracting investor interest by building an AI executive assistant that automates email management and meeting scheduling.
What’s next for upstream?
The battle over the future of email is increasingly tied to which platform can serve both humans and AI agents without having to choose between them. The question for Upstream is whether the next generation of knowledge workers will embrace radically different inboxes or simply wait for Gmail to catch up.
