Simantic, a YC F26 Startup, Swaps Renode for Its Own Rust Firmware Simulator

Simantic, a Y Combinator F26 company, launched a cloud firmware simulator on Hacker News that its two founders say runs on a Rust engine of their own after they abandoned Renode, the open-source simulator maintained by Antmicro. The Launch HN post had 43 points and 12 comments when The Terminal read it on Oct. 29. It gives no prices, and the company's site gives none either.

The founders, Ahnaf and Seungmin, say they are former firmware engineers from Neuralink and Tesla. The post gives first names only, and that biography is theirs, not something The Terminal could check.

What Simantic sells

The Simantic site lists two products. Cloud Sim runs real firmware on simulated microcontrollers from CI, a terminal or an AI agent. Simantic Bot is a reviewer that builds a pull request's firmware, runs it in the simulator and posts one review with tests and suggested fixes.

The site links an HTTP API, a TypeScript SDK (@simantic/cloud-sim) and an MCP server (@simantic/cloud-sim-mcp). A Python package and a command-line tool are labelled "coming soon". The post says the cloud simulator is free to try and that a native binary for local use needs a paid developer plan, with no price attached.

Which chips it actually models

The post says the simulator covers some STM32 F0, F4 and H7 parts, plus the ESP32-S3, ESP32-C3 and RP2040. The site's landing page names one part, the STM32F072RB, in an example, and says it is working toward being the most rigorously tested engine for firmware, using real silicon as the reference. That is a goal, not a result.

A commenter listed what the cloud API returned: STM32F042, F048, F072, F401 and F446, plus ESP32-C3 and RP2040. No H7 and no ESP32-S3 appeared in that list. The founder replied that a full model list would be published later that day. The Terminal did not run the API.

Chip family	Launch post	Commenter's API listing
STM32F0	yes	F042, F048, F072
STM32F4	yes	F401, F446
STM32H7	yes	none listed
ESP32-S3	yes	none listed
ESP32-C3	yes	listed
RP2040	yes	listed

Why Renode was dropped

The founders told commenters the product began as a wrapper around Renode, then moved to a Rust engine. Their reasons, as posted: slow upstream development, .NET performance, bloat and accuracy complaints from users. Those are the founders' characterisations.

The Renode repository shows what they are leaving. It is MIT-licensed, created and maintained by Antmicro, requires .NET 6.0 or later, has about 3,100 stars, and targets ARM Cortex-A, R and M, x86, RISC-V, SPARC, POWER, Xtensa and MSP430X. A new engine has to match that accuracy on every part it claims, and the cost of being wrong is firmware that passes in simulation and fails on a board.

The founders' answer is hardware validation. They said rigs holding development boards, a Saleae Logic MSO and an SWD bus run around the clock to find where models diverge from silicon, and that "the board is king". They promised published benchmarks "in the coming months" and said they will start narrow, with STM32.

One customer, described but not named

The only customer evidence is a space startup, which the founders say tested firmware for hardware it did not yet have at about a hundredth of the cost, in money and time, of building boards. No company is named, and the figure is a founder claim.

A commenter also raised the name's similarity to Symantec. The founder said they own the domain and had considered it.

The pitch is aimed at the same cost problem as the CircuitHub robot that builds a PCB for $630 in four days: hardware iterations are slow, so anything that moves testing off the bench is cheaper. It also sits next to the review-overhead argument in our piece on Brooks's law and AI agents, since Simantic Bot's job is to check agent-written code before a human does.

The next checkable item is the model list and the benchmarks. If the list the founder promised matches the post's claims, ESP32-S3 and the H7 parts will appear on it. If it does not, the post overstated what shipped.