Try it: https://velxio.dev/
Source: https://github.com/davidmonterocrespo24/velxio (AGPLv3)

[3.0.0] - 2026-06-11

Added

• Custom retro CPU chips (Z80, 8080, 4004, 4040, 8086) with programmable ROM, board-less operation, and in-editor assembly support
• MicroSD card emulation over SPI for AVR, RP2040, and ESP32 with FAT16 image and upload panel
• Library Manager with per-board manifests, content-addressed cache, version management, uninstall, and autocomplete
• ePaper display emulation for SSD168x (B/W, tri-colour), UC8159c (ACeP 7-colour), and UC8179 (mono) panels
• Undo/redo for canvas operations (components, wires, moves, rotations, property changes)
• PinResolver abstraction enabling SPICE-resolved digital inputs for mixed-mode simulation
• Full ngspice WASM migration: one solver path across browser and Node tests
• SignalRouter for ESP32 GPIO Matrix routing, replacing the per‑peripheral ad‑hoc cache
• Oscilloscope trigger modes (Auto / Normal / Single) with edge selection and position control
• RP2040 real-time performance: IdleSpinDetector elides busy‑wait loops, WFI sleeps are bounded
• ESP32‑CAM emulation with real webcam frame bridge via QEMU
• Multi‑board wire‑aware interconnect (UART, I2C, SPI, digital pins) across all supported boards
• GitHub Sync, Share/Embed modal, BOM CSV export, schematic PNG export (Pro features)
• Desktop app welcome page, grace/license gating, native menubar bridge, in‑app update toast
• i18n support for 9 locales (en, es, pt‑br, it, fr, zh‑cn, de, ja, ru) across the UI
• Extension hooks for private overlays: auth/DB split, session, save action, agent chat slot
• .vlx project export/import for stateless OSS self‑hosters
• Board options modal, per‑target compilation console with status grouping
• Live compile log streaming for ESP‑IDF (cmake/ninja output) and arduino‑cli
• Visual LED test harness (CDP‑driven) and netlist snapshot tests for all gallery examples
• Over 100 new gallery examples (Pico Doom, ESP32‑CAM preview, ePaper dashboards, retro CPU demos, 100 Days of IoT, analog circuits, etc.)

Changed

• Library Manager redesigned: single unified tab with state‑aware row actions (Add to project, In project toggle, Uninstall/Remove)
• Compilation system: async job model with status polling, request dedup, concurrency semaphore, persistent ESP‑IDF build directory
• ESP‑IDF builds now use ccache with 8 GB cap, per‑variant persistent directories, and graceful fallback for incomplete manifests
• Server‑side library resolution scoped to content‑addressed cache; global volume retired
• ePaper rendering improved: native‑window compose, proper rotation, byte‑aware orientation, paged window union
• Canvas interactions enhanced: wires follow component rotation, minimap with draggable viewport, drag‑to‑move parts during simulation
• Bundle size reduced via manualChunks: main entry dropped from ~23 MB to ~2.68 MB; wokwi‑elements, PiTerminal, mcu‑emulators split
• Landing page refreshed with AI agent section, updated pricing tiers, licensing cards, and live editor hero screenshot
• Pricing copy updated to multiplier messaging (Pro = 20×, Pro Max = 50×)
• Desktop app hides marketing nav, redirects / → /editor, shows splash screen during boot
• CHANGELOG.md entries reflect all new features and changes for v3.0.0

Fixed

• ESP32: WiFi/HTTP client link by enabling mbedTLS PSK; BLE stack switched to Bluedroid; LEDC duty routing for multi‑servo; flash image trimming (10× smaller JSON); sdkconfig defaults for cleaner serial output
• RP2040: delay()‑based sketches now run in real‑time on slow hosts; SPI0 routing fixed for Arduino init; UART TX waveform synthesized
• AVR: serial RX queue so Serial.readStringUntil sees full input; UART TX waveform at bit level; INPUT_PULLUP pin state; LED visualization through SPICE
• Multi‑board: initSimulator no longer wipes Interconnect’s UART wrapper; board removal reconciles running flag
• Canvas: wires follow component rotation; undo/redo state restored; component deletion cascades to wires; sensor panel opens on desktop click; wire color palette works
• i18n: index.html SEO fallback div removed after mount; missing locale keys for admin/user pages added
• Desktop: openExternal works via cascade of IPC paths; native menu routes navigate in‑window
• CI: Frontend Tests restored by patching RP2040 mocks and install‑libraries payload; backend e2e re‑enabled; worker heap limit bumped; cache storage growth limited
• Library: ArduinoJson and other src/‑layout libraries compile correctly by preserving directory structure
• ePaper: BUSY polarity per controller family; RAM Y‑counter wraps at window end; orientation correct across all boards
• Visual LED: RGB LED, 7‑segment, and PWM fade now correctly driven through SPICE‑resolved pins
• PinManager: updatePort respects DDR mask so INPUT_PULLUP does not falsely mark pin as output
• Many other bug fixes across compilation, simulation, UI, and platform compatibility

Performance

• Bundle size reduced by 88% for main entry via manualChunks
• ESP‑IDF warm compiles drop from 5–7 min to 5–30 s with ccache + persistent build dir
• Compilation dedup prevents multiple ninja jobs from racing on the same sketch
• Spice/I2C waveform rendering speed improved by batching SPI bytes in the worker
• Minimap and canvas rendering optimised for mid‑range hardware

Removed

• Legacy SpiceEngine (eecircuit‑engine) and CircuitScheduler replaced by ngspice WASM
• Dead auth/DB dependencies from OSS image (SQLAlchemy, JWT, etc.)
• Per‑board LEDC update fallback after SignalRouter rollout
• Unused files: wireOffsetCalculator, wirePathGenerator, wireSegments
• Global arduino‑libraries volume no longer needed for library resolution