When Firmware Sentry is the right call
Memfault and Firmware Sentry solve the same core problem differently. Here's when each makes sense.
Choose Firmware Sentry if…
- You want crash reporting live today, not after a sales cycle
- You're a startup, solo founder, or small team (under 20 engineers)
- You want AI to explain each individual crash, not just fleet-wide release trends
- You ship on ESP32 or STM32 and want open-source SDK you can read
- You want $59/mo self-serve, not a $3,495/mo quote-only plan
- You want a focused tool, not a full observability + OTA platform
Stick with Memfault if…
- You need full OTA fleet management alongside crash reporting
- You run a large fleet with SLA requirements and dedicated support
- Your budget supports a $3,495+/mo platform with a sales process
- You need Android or embedded Linux support (in addition to MCU)
- You have a dedicated DevOps team to run the integration
- You're already invested in Memfault's broader observability suite
Feature comparison
Verified July 2026 against memfault.com/pricing, Memfault's docs and supplemental terms — including corrections sent to us by Memfault's founder (thank you). Both products ship fast; if any cell is out of date, email us and we'll fix it within 48 hours.
| Feature | Memfault | Firmware Sentry |
|---|---|---|
| Starting price (paid) | $3,495/mo (Growth) — quote required | $59/mo Starter — self-serve, no quote |
| Self-serve signup | Free tier is self-serve, up to 100 devices. Paid plans (Growth $3,495/mo, 1,000 active devices) are quoted. | Yes — every tier, any supported chip, no call |
| Per-crash AI root cause | Release-report AI summaries built in (their docs, Jun 2026); per-crash analysis via their MCP server + your own AI assistant | Yes — every crash gets a plain-English root cause + Cursor/Copilot fix prompt |
| ESP32 support | Yes | Yes — verified on real hardware |
| STM32 Cortex-M support | Yes | Yes — NUCLEO-L476RG verified |
| SDK language | C — source-available on GitHub (custom BSD-style license, use restricted to the Memfault service) | Pure C99 — Apache-2.0, read every line |
| SDK flash footprint | ~4 KB (per Memfault) | ~4 KB — zero heap allocations |
| DWARF symbol resolution | Yes | Yes — automatic on every crash |
| Air-gapped / UART devices | Yes — supported since launch | Yes — UART + gateway.py for any non-networked MCU |
| OTA firmware updates | Yes — full OTA suite | Not yet — crash reporting focus |
| Debugging data retention (Growth tier) | 30 days | 1 year |
| Breadcrumb event log | Yes | Yes — 10-event ring buffer, survives reset |
| Free tier | Yes — 100 devices, self-serve. Commercial teams must keep free-tier devices internal (their terms). Nordic-focused Developer plan runs via nRF Cloud. | Yes — 10 devices incl. commercially fielded units, any supported chip, no card |
| MCP server (AI agent / IDE integration) | Yes — launched 2026 | Yes — 9 tools, live at /api/mcp |
| Target customer | Mid-market and enterprise IoT teams | Startups, indie firmware engineers, small IoT teams |
* Memfault pricing and features based on publicly available information as of July 2026 (memfault.com/pricing, docs.memfault.com), corroborated in part by Memfault co-founder François Baldassari. Verify current pricing at memfault.com.
The one thing Memfault doesn't do yet
Memfault's AI currently analyzes releases, not individual crashes. This is the whole reason Firmware Sentry exists.
Memfault's AI, as of mid-2026, is built into their Release Report — it compares stability and connectivity metrics between firmware versions and flags regressions. Useful for spotting trends across a fleet. But when a single device throws a specific crash, you still get registers, a symbolicated backtrace, and local variables — then you sit down and figure out what went wrong yourself.
Firmware Sentry takes the full crash context — registers, DWARF-resolved frame, CFSR flags, breadcrumbs — and has Claude explain that specific crash in one sentence, every time it happens. Then it gives you a fix prompt to paste into Cursor or Copilot. You go from an individual crash to a fix without opening a debugger.
Root cause: i2c_handle is NULL — sensor_read() runs before
i2c_init() completes after brown-out, at sensor.c:87.
Fix: guard the handle and move i2c_init() ahead of task start.
Cursor prompt: copied to clipboard ✓
How to switch
Switching from Memfault takes about 30 minutes. Here's the path.
Sign up
Create a free account at firmwaresentry.io. No sales call, no credit card for the free tier.
Add the SDK
Clone the Apache-2.0 SDK from GitHub. Add the component to your ESP-IDF or STM32CubeIDE project. Three calls: fs_provision(), fs_init(), fs_log_event().
Upload your ELF
Upload the .elf file for your current firmware build via the dashboard. This enables automatic DWARF symbol resolution on every crash.
Remove Memfault
Remove the Memfault SDK components. The two SDKs use the same underlying fault hook pattern — no hardware changes needed.
Common questions
Does Firmware Sentry support all the same microcontrollers as Memfault?
Not yet — we currently support ESP32 (all variants with ESP-IDF v5.x) and STM32 Cortex-M4 (verified on NUCLEO-L476RG). Memfault additionally supports Android and embedded Linux. More MCU targets are on our roadmap — if you run nRF52, RP2040, or other Cortex-M variants, contact us.
What about OTA firmware updates? Memfault has a full OTA suite.
Firmware Sentry is focused entirely on crash reporting and diagnosis. We don't do OTA updates. If OTA is critical for you, Memfault or a dedicated OTA service (AWS IoT, Azure DFU, custom) is the right choice alongside us.
Doesn't Memfault already have AI features?
Yes — Memfault AI launched in 2025 and, per their docs (June 2026), is scoped to release-report summaries; they also ship an MCP server (all tiers) so your own AI assistant can query fleet data. What we do differently: every individual crash automatically gets a plain-English root cause plus a ready-to-paste Cursor/Copilot fix prompt — no assistant setup, no querying. Both products are moving fast; check their current docs if this is core to your decision.
Can I run both Memfault and Firmware Sentry at the same time?
Technically possible but not recommended — both hook the fault handler. Use Firmware Sentry on its own and you get the full diagnostic picture.
How do I know Firmware Sentry's crash data is accurate?
The SDK is Apache-2.0 on GitHub — you can read every line. All captures are verified on real hardware (ESP32-WROOM-32 and NUCLEO-L476RG). Measured values (14µs capture time, 601B dump size) are published in the datasheet.
How does Firmware Sentry compare to Spotflow?
Spotflow is a strong low-cost option if you're Zephyr-native: their SDK is a Zephyr (west) module with logs-first observability, AI crash analysis, and aggressive pricing (€499/mo per 1,000 devices, vs Memfault Growth at $3,495). We target different stacks — Firmware Sentry is built for ESP-IDF and STM32 Cortex-M, which Spotflow's SDK doesn't cover. Pick by your RTOS.
Is there a free trial?
Yes — the free tier is permanent, not a trial. 10 devices, AI diagnoses included, 7-day crash retention. No credit card required. Upgrade to Starter ($59/mo) when you ship to production.
What happens to my data if I cancel?
Your crash data is retained for the duration of your plan. On cancellation you can export your data; we keep it for 30 days after, then delete it.