esp32sim: a Swedish engineer who spent thirty years writing emulators built an "ESP32 in the browser" with Claude in two months
What it is A free, open-source ESP32 emulator written in Rust. It boots unmodified firmware from the real chip ROM and emulates the screen, touch, sound, and WiFi together. It runs in a web page, and it can also run from the command line as a test board for AI coding tools.
Why it took off AI-written firmware is hot, and everyone is stuck on flashing and testing hardware. It's free, open source, and works offline, which goes straight after the paid Wokwi. The demo runs Linux on ESP32 in the browser, and the author is a veteran emulator researcher, so one Show HN post took off.
BHow you could follow Don't build another ESP32 emulator. If you know a particular chip, use AI to build the same kind of standard open-source browser emulator for RP2350, STM32, or nRF, with a striking demo, and launch it as a Show HN.
- Data (updated daily) · Repo created 2026-08-25 · 1,102 stars · 7 days +169
GitHub · stars Data 2026-10-19 → 2026-11-08 (21 days, 20 observations). Points before 10-28 come from deeply / archive backfill, not every day has one
On 2026 Oct 17, Swedish researcher Joakim Eriksson posted a Show HN: running ESP32 firmware in the browser. The post got 212 points and 50 comments, and in three days the repo went from under 300 stars to 539, reaching 6 by Nov 1076. The category isn't empty: Wokwi has been paid and running for years, and Espressif itself got into it this year. So why did it get stars, and can you pull off the same thing? This piece breaks it down.
"There's no ESP32 in this demo"
The post itself is short, and the key line is:
The fun part of the demo is that there is no ESP32 involved — the firmware is executing in the emulator.
("The fun part is that there's no ESP32 in the demo at all; the firmware runs inside the emulator.")
Open the demo page, nothing to install: an ESP32-S3 running Linux 6.11 that you can log into via shell; a 480×480 LVGL touchscreen; a pocket synth playing C64 SID chiptunes; and a small fish tank whose fish are driven by a tiny transformer model. All of it is real firmware, unmodified, booting in your browser tab from the chip's own mask ROM.
The first comment on the thread gets to the point: "How is this different from Wokwi? They've been doing this for years." Replies split between "this one is vibe coded" and "it's open source and free." The author's own reply:
Wokwi is SaaS emulator with a monthly cost - I need to have a tool for my own vibe coding of new ESP32 software … Free for all, free forever is the plan.
("Wokwi is a monthly SaaS. I wanted a tool to vibe-code ESP32 software myself, and this is that... The plan is to keep it free for everyone, forever.")
What it is
An open-source ESP32 emulator written in Rust, MIT licensed. It goes further than typical emulators: it boots from the chip's mask ROM, runs the real second-stage bootloader, then runs FreeRTOS and your app with no firmware patches. It also emulates the board around the chip: screen, touch, LEDs, buttons, sound, camera, WiFi. WiFi uses Espressif's original driver library, so the firmware can connect to a virtual hotspot, get DHCP, then reach the real network, HTTPS included.
The same code compiles to WebAssembly for the browser and runs as a local CLI, dumping the screen to PNG and audio to WAV. The ESP32-S3 has a JIT and runs hello_world about 30× faster than real silicon; the S3 has been checked instruction by instruction against a real chip over JTAG. It supports five chips: S3, C3, C6, the classic ESP32, and P4, with varying maturity (README, 11-06).
Who is behind it
Joakim Eriksson does IoT research at RISE, the Swedish national research institute. He is a developer of Contiki-NG, the IoT operating system, and a co-author of Cooja, the sensor network simulator. On HN he said he's "been writing simulators since the mid-90s." His X account has only 666 followers. The project didn't take off because of the author's name.
The most commits came from another developer, Alice (904 commits). Joakim made 442, and Mattia Fiumara of the AI hardware design company Schematik made 374. Three people, just over two months, 1700 commits in total.
The author doesn't hide the AI. When a commenter called it "vibe coding," he said it was "built by a simulator developer using Claude," partly from the spec sheets and partly by vibe: "I don't have to read the piles of spec sheets myself. Claude reads them, but you still need to know what you're doing." Others called the README "AI slop," long and messy, and he admitted it and said he'd fix it. By Nov 6, the README had been rewritten into a few short screens with tables.
The core of it: a domain veteran used AI to compress what used to take several person-years of instruction-level emulation into two months.
Why this project got the stars
ESP32 emulators aren't new, and the field has been crowded for 2026 years:
| Who | Format | How it differs from esp32sim |
|---|---|---|
| Wokwi | Web app + VS Code extension, paid at €5.6–8.1/month | De facto standard, but closed source and subscription-based |
| Velxio | Open-source web app, 2026-03 on HN with 196 points, 3618 stars | Lets you draw circuits with wires, supports many boards; the ESP32 runs QEMU on a server |
| Cirkit Designer | Commercial web app; ESP32-S3 simulation added in May | Also instruction-level and Rust-to-WASM, but closed source and focused on Arduino |
| Espressif's official esp-emulator | Repo created in May, 524 stars | Broadest chip coverage, but binaries only and no classic ESP32 |
| Simantic(YC) | Launch HN on 10-29, 80 points | Paid firmware simulation API for AI agents |
(Star counts from GitHub, 11-06)
Taken one at a time, each feature has been done by someone. What's rare is combining MIT open source, self-written instruction-level emulation (not QEMU), a real boot chain, board peripherals, pure browser execution, and a CLI an agent can drive. That explains why experts would star it, but not why it's happening now. Three other things explain that:
Timing. By autumn 2026, using Claude Code or Codex to write ESP32 firmware was already common. The bottleneck was flashing and testing: every change meant plugging in wires and reflashing. The author put it plainly on HN: you can do agentic coding "without touching hardware until the code mostly works, and spend less time flashing." The same month, Espressif's developer blog wrote about Cirkit, and Simantic launched on YC's Launch HN with the same story. That shows the demand is real and growing.
The demo sells it. "Linux on an ESP32, running in a browser tab" is exactly what HN readers click on. It spreads far better than a hello world.
A one-line pitch aimed at the paywall. The project description reads "no hardware, no cloud, no subscription." Commenters volunteered, "I tried Wokwi several times, they want money, it's limiting."
Where users come from
Almost all of it came from that one Show HN and its aftermath:
| Date | Stars gained that day | What happened those days |
|---|---|---|
| 10-17 | — | Show HN, 212 points / 50 comments |
| 10-17–10-19 | Total through 10-19: 297 | A dozen-plus HN mirror sites and bot accounts reposted it (betterhn50, daily.dev, hn.today, etc.); tech blogs in Korea and Malaysia followed |
| 10-20, 10-21 | +127, +115 | Chinese tech accounts on X and Threads recommended it alongside Velxio and Espressif's official emulator ("ESP32 has been hot these two weeks"); r/esp32 had an introduction post |
| 10-28 | +116 | No source found; the same week, Espressif's blog, MakeUseOf, and Simantic kept the topic warm |
| Last 7 days | +199 (+7 over the first 293 days) | Cooling down |
(GitHub daily numbers, 11-06)
It never made GitHub trending. No mainstream embedded outlets like Hackaday or CNX Software covered it (search found nothing). On r/ClaudeAI someone wrapped it as an MCP server plus a skill so Claude Code could boot and test its own firmware inside it. That wrapper, esp32sim-mcp, had 11-06 stars as of 7. The people who wrap it don't get the stars. The stars go to the hard thing underneath.
The next wave of demand is in the comments
The Show HN comments are worth reading in full. They're a ready-made list of requests:
- "Any RP2350 support?" The author said esp32sim doesn't have it, but his other project Cooja-NG already has RISC-V and ARM Cortex-M33, "so it's not hopeless."
- "Planning to support P4?" The author answered "in a few weeks"; in 11-06's README, P4 is already marked as a draft.
- "What about H2?" "Does it support ESP-NOW and mesh?" "Could I preview WLED light effects with it?" "I want to test Meshtastic firmware without bricking my device."
- Someone building ESP32 golf hardware said a browser-based ESP32 is a "superpower" for hardware vendors: you can put the product, with pixel-accurate screen and sound, straight into users' hands before they buy.
If it were you
Grade: B. Another ESP32 emulator won't get stars now. In three months, the field has filled up with Espressif's official tool, Cirkit, Velxio, and Simantic. What's worth following is the approach: a domain veteran plus AI, building a chip that had no good open-source browser emulator, with a striking demo, launched through one Show HN. The playbook is clear, but the barrier is whether you yourself understand the chip.
Who it suits: embedded developers who have written emulators, built BSPs or drivers, and can read a chip reference manual; people with real boards to run comparison tests on; people who can explain exactly what makes their emulation "real" (real ROM boot, instruction-by-instruction comparison with the chip) and withstand expert questioning on HN.
Who it doesn't suit: people who haven't worked close to the metal and expect AI to explain the chip for them. The comments went after "vibe coded" and "AI slop" on day one, and only the author's background held up. And anyone planning an "agent-facing MCP wrapper": esp32sim-mcp's 7 stars already show how that turns out.
How to do it: pick a different chip. The comments already named them: RP2350 (Raspberry Pi Pico 2), STM32, nRF52/nRF54 all have large hobbyist communities, and no open-source, complete, browser-level emulation has become the accepted choice for any of them. Follow esp32sim's standard: boot from real ROM or the real reset vector, run unmodified official SDK firmware, include board peripherals (at least one common display dev board), use the same code for the WASM web version and the CLI, MIT license, and publish comparison tests against the real chip in the docs. Keep the README short from the start so there's no "AI slop" to point at.
How to get stars: the demo page is everything. Pick the most famous firmware in that chip's community (running MicroPython, running Linux, playing retro music, running a small model) and make it work with one click. Write the one-line description against the existing paid options ("no hardware, no cloud, no subscription"). Launch with a Show HN titled in the same format, "Run X firmware in the browser," and answer every comment yourself. The next day, post in the matching subreddits (r/raspberry_pico, r/embedded), and turn the demo into a short video. Put a line on the homepage such as "a test bench your coding agent can drive" to catch the people now using AI to write firmware.
Timing: ship before Q1 2027. Right now the topic "AI writes firmware, but there are no virtual boards" is hot, and chipmakers are getting involved themselves (Espressif opened its repo in May). Once Raspberry Pi or ST release an official emulator, this position is gone.
Signs you've misread it: ① Raspberry Pi, ST, or Nordic launch an official browser emulator before you do; ② your Show HN doesn't reach 100 points and the comments focus on "how is this different from Wokwi," meaning that chip is already covered; ③ esp32sim adds RP2350 within a few months (the author has the Cooja-NG background and said "it's not hopeless").
A closing note for people building open source: once AI cuts the cost of low-level engineering, what's scarce isn't people who can write code. It's people who know what "done right" looks like. esp32sim's stars aren't for Claude. They're for an emulator that convinces experts.
Research notes: competitor table, acquisition evidence, full research report
- Competitors
Name Where Launched Scale How it differs from this one Wokwi Web About ¥2019–2020 The ESP32 emulation standard, paid at €5.6–8.1/month; user numbers unverified Closed-source SaaS with a subscription; esp32sim is MIT open source and runs offline from local or static web pages Velxio Open source 2026-03 3618 stars (GitHub repo 11-06), HN 196 points Multi-board circuit-wiring platform; the ESP32 runs QEMU on a server. esp32sim is a self-built instruction-level emulator, pure browser Cirkit Designer ESP32-S3 simulator Web 2026-05-05 Unverified; coverage in Espressif's developer blog and on Hackster Also Rust/WASM instruction-level, but closed-source commercial and focused on Arduino sketches. esp32sim is open source, multi-chip, and its CLI works for agents espressif/esp-emulator (Espressif official) Big-company features 2026-05-13 524 stars (GitHub repo 11-06) Broader chip coverage (C5/H2, Bluetooth, GDB) but binaries only, no classic ESP32, and the web version doesn't go online Espressif QEMU fork Open source Years Not verified No board peripherals and no browser experience Simantic(YC F26) Other 2026-10-29 Launch HN Startup, 80 points on HN Paid, closed-source firmware simulation API for agents; esp32sim is free and local PICSimLab Open source 2015 680 stars, stalled Teaching-oriented desktop multi-MCU tool; ESP32 support is shallow - Where users come from
- Verified Show HN: 2026-10-17 author posted Show HN, 212 with 50 comments (hackernews library); stars went from about 300 to 539 in two days
- Verified HN aggregator / reposting sites: betterhn50, h4ckernews, daily.dev, hn.today, bedrocknews and about 10-17~18 other reposts; hamradio.my 10-21, techbriefe 10-24 long-form pieces (Exa)
- Verified Chinese X / Threads / Mastodon: @iluciddreaming, Potato Brother (Mastodon 10-19), Threads @cxuanai / @zengjixiang0401 10-20 recommending it alongside Velxio and Espressif's esp-emulator
- Verified Reddit: an intro post in r/esp32; an r/ClaudeAI post about esp32sim-mcp; score not retrievable (403)
- Verified Author and collaborator network: LinkedIn posts from Mattia Fiumara (Schematik) and Joakim Eriksson; Joakim's X has only 666 followers
- Verified YouTube / Instagram reposts: YouTube intro video and Shorts; Default RED Systems 10-18 on Instagram/LinkedIn
- Inferred 10-28 second wave: +116 in a single day, source not found; during the same period the Espressif blog, MakeUseOf and Simantic kept the topic warm
mikroverk/esp32sim: why it runs
Research date 2026-11-06. Data sources: our github / hackernews libraries (agent-im server), GitHub API, Jina / Exa / Brave web search. Anything unverified is marked as such.
One line
esp32sim is an open-source ESP32 simulator written in Rust. It boots from the chip's own mask ROM, runs the real second-stage bootloader, then executes unmodified firmware. It also simulates the board's screen, touch, LEDs, sound, camera and WiFi, and there's a WebAssembly build that runs right in the browser. It got its first wave of traction from a Show HN (10-17,212 points / 50 comments), then kept spreading through Chinese X/Threads posts, aggregator sites and r/esp32. The timing hit the hot topic of 2026 autumn: AI writing firmware, which needs a virtual board to run tests without any physical wiring.
1. Basic data
| items | value | Source |
|---|---|---|
| Repo created | 2026-08-25 (originally at joakimeriksson/esp32sim, moved after the mikroverk organization was set up 2026-09-28) | GitHub API; Jina search results still include old pages for joakimeriksson/esp32sim |
| Version | v0.1.0 09-02, v0.2.0 09-13, v0.3.0 10-20 | GitHub releases |
| Stars / forks | 1076 stars / 73 forks (11-06); fork/star ratio 6.8% | github library repo_profile |
| past 7 days | +199 (first 7 days +293), cooling down | GitHub repo |
| Single-day peak | 10-20 +127, 10-21 +115, 10-28 +116 | github repo_day |
| Contributors | aliceisjustplaying with 904 commits, joakimeriksson 442, mfiumara 374, the rest from single digits to dozens | GitHub contributors API |
| trending | Has never made any daily trending chart (trending_days_any=0) | GitHub repo |
Star curve (GitHub repo): 10-19 297 → 10-20 424 → 10-21 539 → 10-24 641 → 10-27 681 → 10-28 797 → 11-01 933 → 11-06 1076. Before the Show HN, the star history in the repo doesn't have it (this repo only enters deeply's history on 10-19), but Threads @cxuanai's archived post from 10-20 recorded 435 stars (archived by genai-insight.com), which matches our 10-20 424.
2. Who the author is (this matters)
- Joakim Eriksson: researcher and manager in IoT at Sweden's RISE research institute, Contiki-NG developer, co-author of Cooja (the sensor network simulator), and co-founder of the Jfokus conference. On HN he says he has been writing simulators since the mid-90s. His X account @JOAKlM has only 666 followers, so this is not personal-influence driven.
- Alice (@aliceisjustplaying): the most prolific committer.
- Mattia Fiumara: works at Schematik (AI hardware design); posted a promo on LinkedIn; has a fork at schematik-engineering/esp32sim on GitHub.
- The author publicly admits it was built by "an emulator veteran + Claude": "partly spec-driven partly vibed… Claude reads the spec sheets, but you need to know what you're doing" (HN comment 50139022). HN commenters criticized the README as "AI-slop, too long", and the author promised 0.3.0 to revise it.
In other words, this is a domain expert using AI to build in two months an instruction-level emulator that would have taken several person-years before. Its feature density is far beyond a typical new library (ESP32-S3 with JIT, runs Linux 6.11, runs a small transformer with 14.3M parameters, connects to real-network WiFi over HTTPS, and lockstep-compares against real chip JTAG).
3. Competitors
| Name | Form | Launched | Scale | How it differs from esp32sim |
|---|---|---|---|---|
| Wokwi | Web SaaS + VS Code extension + CLI | Around 2019 (the wokwi/rp2040js repo was created 2021 years ago) | The de facto standard for ESP32 simulation; paid tier €5.6–8.1/month (wokwi.com/pricing); scale not verified | Closed-source core, monthly fee, requires an account; esp32sim is MIT-licensed open source and runs offline locally or as a static web page. The author said on HN that he built it because Wokwi is "SaaS with a monthly cost". |
| Velxio | Open-source web app (AGPL) | 2026-03 | 3618 stars, 387 forks (github library 11-06); 2026-03 HN points 196; a feature article on the Espressif developer blog 07-31 | Drag wires to draw circuits, supports many boards (Arduino, Pico, Raspberry Pi); for ESP32 it runs QEMU on a server and pushes pin states back to the web page. esp32sim is a self-built instruction-level emulator that runs purely in the browser with no server dependency. |
| Cirkit Designer ESP32-S3 simulator | Commercial web app (circuit design + AI) | 2026-05-05 launch; covered by the Espressif developer blog 10-26 and Hackster | Not verified | Also "instruction-level, written in Rust, compiled to WASM", but embedded in a closed-source commercial product focused on Arduino sketches. esp32sim is open source, runs locally via CLI, and supports multiple chips. |
| espressif/esp-emulator (Espressif official) | Binary releases, web version + local version | Repo created 2026-05-13 | 524 stars (github library, 11-06,7 days +24) | Broadest chip coverage (C3/C5/C6/H2/P4/S3, Bluetooth, Thread, GDB), but it does not include the classic ESP32, the web version does not connect to the internet, and whether the source is open is undecided (per Threads @cxuanai's summary) |
| Espressif QEMU fork(espressif/qemu) | Open source | Years | Below the 50-star threshold, not in the databases; actual star count unverified | Does not emulate board-level peripherals (screen / touch / sound); no ready-made browser experience |
| PICSimLab | Open-source desktop | 2015 | 680 stars, stalled | Teaching-oriented, multi-MCU, shallow ESP32 support |
| Simantic(YC F26) | Commercial APIs | 2026-10-29 Launch HN (80 points) | Startup | Sells a "firmware simulation API for AI agents"; its positioning overlaps with esp32sim's "hardware test bench for coding agents", but it is paid and closed-source |
| BoardLab / Babe32 and others | Small web app | 2026 | Show HN with 3 points, no scale | Far less capable |
Conclusion: this category is crowded, and it clearly heated up in the second half of 2026 (Espressif itself got involved, and Cirkit, Velxio and Simantic all appeared in these months). esp32sim is not the first, but it is the only one that is simultaneously open source (MIT), built on its own instruction-level emulation (not relying on QEMU), zero-install in pure browser, complete with board-level peripherals, and drivable as a CLI by agents.
4. Growth tactics (where users come from)
- Show HN (confirmed, main channel): 2026-10-17, the author joakimeriksson posted "Show HN: Esp32sim – Run ESP32 firmware in the browser", with 212 points / 50 comments (hackernews library). Over the next two days stars rose from about 300 to 539, with single days of +127 and +115. Top comments: Wokwi charges money, while open source can be used freely; AI agents writing firmware don't have to flash repeatedly; hardware vendors can put products "in a web page for people to try".
- HN aggregators and reposts (confirmed): betterhn50 (X), mastodon @h4ckernews, daily.dev, hn.today, bedrocknews, iodigest, computerical, WiredGuide and more than a dozen other sites reposted it between 10-17 and 10-18 (Exa search results). hamradio.my ran a long write-up dated 10-21, techbriefe 10-24, and Korea's braindetox.kr 10-19.
- Chinese-language X / Threads (confirmed): @iluciddreaming (X) "runs ESP32 firmware directly in the browser", Mastodon's Potato Brother 10-19, and Threads @cxuanai / @zengjixiang0401 10-20 recommending it alongside Velxio and Espressif's esp-emulator ("ESP32 has been genuinely hot these past two weeks, and Espressif itself made an emulator"). Actual reach unverified.
- Reddit (posts confirmed, popularity unverified): r/esp32 "esp32sim: an ESP32 emulator in Rust/Wasm that boots unmodified…"; r/ClaudeAI has someone posting "Claude Code can now boot and test the ESP32 firmware it writes", which is esp32sim-mcp, an MCP server + skill that lets Claude Code run the firmware it just wrote inside esp32sim. Reddit page 403 scores not readable.
- Video / security circles (confirmed): an intro video and Shorts on YouTube, posts from Default RED Systems 10-18 on Instagram/LinkedIn, and mentions in Hackster × Embedder's feed.
- Author network (confirmed, small): Mattia Fiumara's LinkedIn post and Joakim's LinkedIn post (tied to a startup's activities).
- 10-28 second wave +116 (cause unverified): in the same period there was the Espressif developer blog's 10-26 Cirkit article, MakeUseOf's 10-26 piece on Espressif's AI coding assistant, and Simantic's 10-29 Launch HN, so the topic was heating up. However, no post was found that directly points to esp32sim.
- Not found: paid promotion, signs of star-farming (fork/star ratio 6.8% looks normal; contributors include real external PRs), GitHub trending boosts (never made the chart).
5. Why it charted
- The timing of "AI writes firmware, but there's no virtual board": In autumn 2026, writing ESP32 code with Claude Code / Codex was common, and the bottleneck was flashing and testing. The esp32sim homepage literally says "a hardware test bench that a coding agent can drive"; an HN comment reads "agentic coding of ESP32 software – less time spent flashing"; someone on r/ClaudeAI has already packaged it as an MCP. In the same week, Espressif, Cirkit and Simantic were all telling this story, which suggests the demand is real and growing.
- Show HN demos that sell well: click through and you see Linux running on an ESP32-S3 with a 6.11 login shell, an LVGL touchscreen, C64 SID music, and an LLM-controlled fish tank. "Linux-on-ESP32 in the browser" demos naturally score on HN.
- "Free, open source, offline" aimed squarely at Wokwi's paywall: an HN commenter wrote "I have tried to use wokwi… They want you to pay and that's limiting"; the author replied "Free for all, free forever". The project blurb is the same positioning: "no hardware, no cloud, no subscription".
- Technical credibility: the author is a veteran of Contiki-NG / Cooja research. Real ROM → bootloader → unmodified firmware; lockstep comparison against JTAG on real chips; the README says it only references QEMU semantics and copies no code. That's what makes experts willing to star it (73 forks, outside contributors sending PRs).
- AI let a small team build a big engineering project: three people, two months, 1700+ commits covering 5 chips, two CPU architectures, a JIT, WASM, and a dozen-plus boards. That level of completeness is missing from comparable open-source projects (PICSimLab, BoardLab, Babe32).
6. Differentiation, and whether that's why it took off
- The differentiation = open source MIT + in-house instruction-level emulation + a real boot chain (no patches) + board-level peripherals + pure browser + usable as a CLI for agents. Each item has been done by someone: Wokwi has strong board-level peripherals but is closed and paid; Velxio is open but runs QEMU server-side; Cirkit is also Rust/WASM instruction-level but closed commercial; Espressif's official emulator covers many chips but isn't open source and lacks the classic ESP32. Only this one has all five.
- Is that the reason? Yes, but it only explains why people who know the field starred it. "Why now" comes down to timing (the AI-written firmware craze plus this past two weeks' emulator buzz in the ESP32 circles) and one successful Show HN. After HN, daily growth dropped from 100+ to 10–40,7 days, and the growth rate fell from 293 to 199. That means no lasting distribution channel formed, and it never made Rust's trending page.
7. Visibility
The buzz so far: Hacker News at 212 points, reposted by a dozen-plus HN aggregators, recommended by a few tech accounts on Chinese X/Threads, and picked up by long-tail blogs like hamradio.my. No coverage from major outlets like Hackaday, CNX Software or The Verge (none found in search), no evidence of big-name influencers reposting it, and the author's X account has 666 followers.
8. Copycats / derivatives
- Ecosystem spin-offs: esp32sim-mcp (r/ClaudeAI, packaging it as an MCP + skill for Claude Code).
- Many same-name forks (schematik-engineering, Xorlev, igouss, influvio, etc.). These are normal forks, not plagiarism.
- Same direction but not copies of each other: Cirkit (out since May), Espressif's esp-emulator (repo created in May), Simantic (10-29 Launch HN). The category is being squeezed by several players at once.
9. What others can learn
- Hit a pain point that existing paid SaaS charges for, head-on, with "free + open source + offline", written right into the blurb.
- The demo page has to "run on click and surprise you": a Linux shell, an LLM, and retro music spread far better than hello world.
- Repackaging developer tools as a "testbed for coding agents": the same simulator, but in 2026 its pitch was that agents can drive it.
- A domain veteran plus AI can produce in two months foundational engineering that used to take several person-years. The method can be copied to other MCUs (RP2040/2350, STM32, nRF). The author's own Cooja-NG has already shipped a browser WASM version 0.4 on 10-29.
10. Still unclear
- Direct source of 10-28's +116 in a single day not found.
- The scores on the two Reddit posts and the view count on the Chinese X post were not read (Reddit 403, X requires login).
- User counts for Wokwi and Cirkit were not verified.
- Actual usage: stars are not usage. Web demo traffic and release download counts were not checked.
- Whether Schematik (Mattia's company) plans a commercial product built on it was not verified.
Sources
- github.com/mikroverk/esp32sim ;mikroverk.github.io/esp32sim/
- news.ycombinator.com/item?id=50131189 (Show HN, 10-17,212 points)
- GitHub repo_profile / repo_day (mikroverk/esp32sim, espressif/esp-emulator, davidmonterocrespo24/velxio)
- hackernews library: Velxio 2.0 (2026-03-27,196 points), Simantic Launch HN (2026-10-29,80 points), BoardLab Show HN (2026-08-21,3 points)
- genai-insight.com/pulse/notes/2026-10-20-esp32-simulators-ve… (Threads @cxuanai, archived copy)
- hamradio.my/esp32sim-open-source-esp32-emulator-browser/ (10-21)
- www.cirkitdesigner.com/blog/2026-05-05-esp32-s3-simulator ;developer.espressif.com/blog/2026/10/cirkit-esp32-s3-browser…
- developer.espressif.com/blog/2026/07/velxio-browser-based-es…
- wokwi.com/pricing
- www.reddit.com/r/esp32/comments/1xacibz/ ;www.reddit.com/r/ClaudeAI/comments/1xa973t/
- x.com/JOAKlM ;x.com/iluciddreaming/status/2111993741892608196 ;x.com/betterhn50/status/2111528171682087289
- www.linkedin.com/posts/defaultred_cybersecurity-infosec-hack…