Comparison

Helioclock vs. HamClock vs. OpenHamClock

A factual feature comparison. Last verified July 2026.

A note on fairness: HamClock (original, by the late Elwood Downey WB0OEW) and OpenHamClock (accius/K0CJH) are both free, open-source, and actively used by thousands of hams. OpenHamClock in particular is a genuinely serious, actively developed project with a real contributor community. This table is meant to help operators pick the right tool for their situation, not to claim Helioclock wins every category — it doesn’t. Where a feature genuinely doesn’t exist yet in Helioclock, or where a competitor does something well, that’s marked honestly.

Why the comparison looks the way it does: Helioclock is built by one developer with a broadcast meteorology and broadcast systems design background, working end-to-end with modern AI development tools — not a decade of one person’s solo nights-and-weekends work (the original HamClock), and not a dozens-of-contributors open-source patchwork (OpenHamClock, which credits AI-assisted development too — that’s not the differentiator here). That’s why several categories below look unusual for a “ham radio dashboard”: the meteorology depth (GOES cloud overlay, GOES GLM lightning, VAAC/USGS volcano data aggregated directly from observatories worldwide, NASA FIRMS wildfire, JTWC tropical tracking, SST/SSTA) reads more like a broadcast weather system than a typical shack display, because that’s exactly where it came from. And it’s why the design is one coherent vision throughout — the MP/DP/Carousel system, the color palette, the alert design — rather than assembled from many contributors’ individually-reviewed panels.


The short version

HamClock (original) OpenHamClock Helioclock
Price Free Free (donations welcome) Paid — SD card $39 (launch special, normally $49), USB stick $39 (launch special, normally $49), turnkey appliance $369, multi-display multi client server, with optional rack mount $499+
License MIT, open source MIT, open source Commercial
Setup required Flash OS, compile/select a fixed resolution, run installer, configure Install Node.js (correct version — the OS-packaged one is too old), clone repo, run npm ci, edit a .env config file in a terminal, optionally set up systemd yourself None — arrives preloaded/turnkey, boots straight to the dashboard
Runs on Raspberry Pi, ESP32, desktop build (fixed resolution per build) Any browser (desktop, Pi, tablet, phone) — but self-hosting means you’re the system administrator Dedicated Pi 4/5/N100 hardware, your existing Pi 4/5, or a Bring-Your-Own PC via the Live USB Stick, browser-accessible — see System Requirements
Active development Original author WB0OEW is a Silent Key (Jan 2026). A community-run backend (hamclock.com) keeps existing installs’ data feeds alive past the June 2026 shutdown, but the original codebase isn’t seeing new features. Yes — very actively developed, frequent releases, 28+ contributors, real community (Discord/Reddit/Facebook) Yes — actively developed, single accountable developer with AI assistance for rapid troubleshooting and rapid deployment of new features.
Support if something breaks Community forums/lists GitHub issues, community Community forum, Direct developer contact

Zero Linux skills, zero installation — the real difference

Helioclock. It just works. No need for an SSH terminal. No .env file. No 11pm troubleshooting.

This is where the comparison actually turns on hardware and setup, not feature checklists. All three products can show you a DX cluster panel. Only one of them requires nothing more than plugging in a device.

There’s excellent free software here for hams who want to run their own Linux box. If that sounds like a fun Saturday, more power to you — genuinely. If it doesn’t, that’s the actual product being sold: free, as long as nothing goes wrong. $49 buys the version where it already went right.

Building your own gear from a kit used to be the hobby — Heathkit, a soldering iron, and a weekend. That era had its charm, but nobody’s buying a modern rig expecting to build it first. You buy a radio expecting it to work when you turn it on. Helioclock is that same expectation, applied to the dashboard sitting next to it.

HamClock (original): You flash an OS image yourself, choose a fixed build resolution up front (800×480 / 1600×960 / 3200×1920 — no changing your mind later without reflashing), and work through a multi-page Setup screen. Reviewers who’ve done it describe real hiccups even with prior Linux experience.

OpenHamClock: Explicitly a self-hosted web app. Their own documentation requires: installing a specific modern Node.js version (v20.19+/v22.12+) because the version Ubuntu ships via apt install nodejs is too old and “will not work”; cloning the GitHub repo; running npm ci from a terminal; and hand-editing a hidden .env file (their own FAQ has a dedicated entry on how to even find a dotfile in a Linux file manager). A one-line Pi installer script exists and helps a lot — but you’re still expected to SSH in, read a systemd service log with journalctl, and know what a git pull update process means if something needs fixing. This is a genuinely well-built piece of software, but “genuinely well-built” and “zero Linux skills required” are different claims, and OpenHamClock’s own docs don’t claim the second one.

Helioclock: Three ways to get running, none of which touch a terminal: – SD card (SKU1) — arrives preloaded, drop it in your existing Pi 4/5, power on. – USB stick (SKU2) — a full bootable drive for most existing x86 PCs (2013 or newer) — see System RequirementsTurnkey appliance (SKU3/SKU4) — dedicated hardware, arrives fully assembled, plug in a monitor and power.

No OS flashing, no resolution to pre-select, no .env file, no npm, no systemd, no SSH. This is the actual product thesis: HamClock and OpenHamClock are excellent free software for hams willing to be their own sysadmin; Helioclock is a device you buy that already works.


No central server — no single point of failure

Every Helioclock unit talks directly to the original public data sources — NOAA, USGS, POTA, SOTA, CelesTrak, and so on — with no Helioclock-operated server sitting in between as a dependency. If the company disappeared tomorrow, an already-deployed Helioclock keeps working exactly as it does today, because it was never depending on a Helioclock server to function. The same holds true for ordinary internet outages: static overlays (basemap, terminator, city clocks) work with zero internet at all, and live data layers simply hold their last update until the connection returns — no crash, no blank screen. The only thing Helioclock’s own infrastructure is used for is optional software updates (via GitHub Releases), not live data.

That’s a meaningfully different architecture from both alternatives, and it’s not a hypothetical — it’s already playing out with the original HamClock:

  • HamClock (original): With WB0OEW’s passing and the original clearskyinstitute.com feeds shutting down in June 2026, the entire installed base now depends on keeping working by pointing at hamclock.com, a single volunteer-run community backend. That’s a brand-new central dependency the original design never had — if that one backend goes down or its maintainer stops, every HamClock relying on it goes with it.
  • OpenHamClock: Genuinely self-hostable, but by default a self-hosted instance still depends on two centrally-run services operated by the project: the DX Spider Proxy (DXSPIDER_PROXY_URL — “a default proxy is provided”) and the ITU-R propagation service (ITURHFPROP_URL — “defaults to the public OpenHamClock service”). Unless an operator deploys their own copies of both, DX cluster data and propagation predictions across potentially thousands of self-hosted units depend on servers operated by one maintainer. And the zero-setup option most casual users will actually reach for — opening openhamclock.com directly in a browser — is itself a single hosted website.
  • Helioclock: No equivalent dependency exists. Each unit is a fully independent node talking straight to the original data sources.

Panel architecture

Feature HamClock OpenHamClock Helioclock
Configurable on-screen panels Small number of fixed pane slots; each slot shows one selectable content type at a time Dockable panels, manually added/resized/arranged in a fixed layout Many small Mini Panels (MPs), freely arranged anywhere on screen
At a glance viewing (MP) of the most important details, plus drill-down (DP) to full details No — a pane just displays its assigned content directly No dedicated drill-down; panels show their full content in place Yes — click any MP to open its full Detail Panel (DP)
Auto-rotation of content Yes — a chosen collection of content types rotates through the same small set of fixed pane slots No — layout is static once arranged Yes — Carousel Mode rotates through saved Favorite Arrangements, each capturing its own panel layout and map layer toggle state, not just which MPs are showing
Effective number of data categories visible/monitorable Limited by the small number of physical pane slots, even with rotation Limited to whatever fits the static dockable layout at once Effectively unbounded — Carousel Mode lets far more MPs cycle through than could ever fit on one screen, each still one click from full detail

The practical difference: HamClock’s rotation cycles content through multiple fixed-size slots, and OpenHamClock’s layout is arrange-once-and-done. Helioclock’s Mini Panel + Carousel system is built to scale past what any single screen can show — you’re not choosing between “a few things showing fully” and “everything squeezed in tiny,” you get a continuously cycling scan of many compact tiles with full detail one click away on any of them.

Visual design & display

Feature HamClock OpenHamClock Helioclock
Display resolution Fixed builds only — compiled for 800×480, 1600×960, or 3200×1920. No true 4K UHD (3840×2160) build. Browser-rendered — scales to whatever monitor it’s opened on Native 4K UHD canvas rendering, purpose-built for large/high-res displays. Plus, will work on any monitor via a web browser.
Rendering approach Native embedded graphics (fixed layout per resolution) Standard responsive web UI, four selectable themes (Dark, Light, Legacy terminal-green, Retro 90s-style) Custom-designed dark UI with layered transparency/glass-panel effects, animated map overlays, and a cohesive gold/cyan/green color system built specifically for at-a-glance readability on large signage-style displays
Visual theming Fixed, utilitarian Standard web styling; Legacy/Retro themes are intentionally nostalgic/utilitarian by design, not glossy Custom color palette + self-hosted display fonts (Orbitron, Share Tech Mono, Barlow Condensed, IBM Plex Sans) designed to look intentional, not like a generic dashboard

Data sources & spotting

Feature HamClock OpenHamClock Helioclock
DX Cluster (DX Spider) Yes Yes (DX Spider Proxy, HamQTH, DXWatch, or Auto — configurable) Yes
Reverse Beacon Network (RBN) No Not built as its own panel Yes
PSK Reporter No (native) Yes — MQTT real-time + HTTP fallback, TX/RX tabs Yes, as its own panel — just excluded from the Best Band Now confirmation logic, see note below
WSJT-X / JTDX live UDP integration Yes (double-click station sets DX) Yes — full UDP listener, plus a relay agent for cloud-hosted instances Yes — live UDP listener, MP/DP panel showing decoded callsigns, signal strength, mode, and frequency offset in real time (map layer of decoded stations planned)
POTA / SOTA / WWFF Yes (POTA/SOTA) Yes (plus WWBOTA) Yes (POTA, SOTA, WWFF, and WWBOTA)
DXpeditions tracker Not confirmed Yes (NG3K-sourced) Yes — MP/DP combo
Contest calendar Yes Yes (WA7BNM-sourced) Yes, but ships with no default feed configured — user supplies their own feed URL, such as WA7BNM’s feed.
Multi-language interface No Yes — 10 languages No
DX news ticker/crawl No Yes (DXNews.com scrape) Yes — matches this, not a differentiator either way
Visible planets panel (positions/visibility) Not confirmed Not confirmed Yes — appears to be unique to Helioclock

Why Helioclock excludes PSK Reporter and POTA from its Best Band Now confirmation logic specifically: both were tested against real data and found to read “zero” for most operators most of the time — not because the sources are broken, but because PSK Reporter only shows activity while you’re actively transmitting a digital mode, and any single QTH’s nearby POTA parks are rarely all active simultaneously. A technically honest zero that looks like a bug isn’t good UX, so both were excluded from that specific confirmation logic. Both still exist as their own panels and map layers elsewhere in Helioclock — PSK Reporter and POTA/SOTA data aren’t gone, they’re just not part of the Best Band Now calculation.

Propagation intelligence

Feature HamClock OpenHamClock Helioclock
Propagation prediction model VOACAP ITU-R P.533-14 (the current international standard), with real-time corrections from live ionosonde measurements when available Own model — MINIMUF-85 secant-law, explicitly documented as “not a VOACAP replacement”; optionally paired with an RTL-SDR dongle (sold separately) for real-world reception confirmation
DRAP (D-region absorption) map Yes No Yes — MP/DP combo plus its own map layer
Prediction vs. live-confirmation cross-check No No Yes — “Best Band Now”: QTH-anchored MUF prediction compared directly against live DX Cluster + RBN activity, with a 4-state result (Confirmed / Likely / Surprise Open / Closed) and hysteresis to prevent flapping
Band conditions summary Via VOACAP graph Yes (N0NBH feed) Yes (band conditions + MUF Matrix)
Multi-day propagation forecast Same-day VOACAP graph only Not confirmed Yes — confirmed 3-day forecast, 9-band × 3-day grid in the detail panel
Decision history / reliability log No No Yes — every best-band pick change is logged, retrievable via API
Real-world reception confirmation (RTL-SDR) No No Yes — an RTL-SDR dongle (sold separately by third parties, not by Helioclock) plugged into the device runs actual reception tests at WWV/WWVH and NCDXF beacon frequencies, confirming propagation because your own hardware is hearing the signal, not because another station reported a spot
SDR receiver / waterfall application (OpenWebRX) No No Yes — OpenWebRX runs on the same device, tune and listen to HF bands directly, no separate computer or software needed

OpenHamClock’s propagation model (ITU-R P.533 plus real ionosonde corrections) is a more rigorous prediction engine on its own than Helioclock’s secant-law model. Helioclock’s differentiator isn’t a better prediction model — it’s being the only one of the three that checks its prediction against live spot data and tells you when they disagree. RTL-SDR reception confirmation takes that a step further: instead of relying on someone else’s spot report, the device is actually hearing the signal itself, which is a real step up from spot-based confirmation and makes Best Band Now’s results that much more trustworthy.

Space weather

Feature HamClock OpenHamClock Helioclock
Solar Flux Index (SFI) Yes, 30-day history Yes, 30-day history Yes, with trend history
Sunspot number (SSN) Yes Yes Yes, with trend history
Kp / geomagnetic index Yes, 7-day history + forecast Yes Yes
X-ray flare class (GOES) Yes Yes, 6-hour chart Yes, with a chart in the DP
NOAA G/S/R space weather scales (explicit 1–5 scale labels) Yes Not shown as explicit G/S/R scales (SFI/Kp/X-ray shown directly instead) Yes
Solar wind (density/speed/flux) Yes Not built Yes (NOAA RTSW real-time feed), displayed as dials for at-a-glance readability
Aurora / OVATION overlay Yes (map style) Yes (NOAA OVATION model plugin) Yes
Dst index Not found Not found Yes (USGS) — appears to be unique to Helioclock
NASA SDO solar imagery Yes Yes (solar image view) Yes, full compliment of imagery and data.
Lunar phase / EME planning Yes Yes (illumination %, next full/new moon) Yes — both as MP/DP combos, plus a full EME link budget calculator (moon distance, path loss, ERP, margin vs. JT65/Q65/CW thresholds for a remote station entered by grid or lat/lon) — neither competitor has anything like this

Map projections & views

Feature HamClock OpenHamClock Helioclock
Available projections Mercator, Azimuthal Mercator-style (Leaflet.js) Mercator, USA/CONUS, 3D rotating Globe, Azimuthal
Dedicated USA/CONUS regional view No — generic Mercator zoom only, no purpose-built regional mode No — generic pan/zoom on a single world map Yes — dedicated USA view with Alaska/Hawaii insets
3D rotating globe view No No Yes — real-time solar illumination on a rotating sphere, with lightning/earthquake/volcano icons rendered directly on it
Selectable base map styles Political/Terrain choice, DRAP/Aurora/seasonal Static tile styles 7 styles: Day/Night ocean-detail, Day/Night plain-ocean, Satellite day-only, Seasonal ocean-detail, Seasonal plain-ocean, Political, Outline

Software updates

Feature HamClock OpenHamClock Helioclock
Automatic update checking Yes — configurable auto-upgrade schedule in Setup Yes — opt-in via .env (AUTO_UPDATE_ENABLED), periodic GitHub check Yes — daily check with randomized time offset, no configuration needed
Manual/on-demand update trigger Yes — tap the version number Yes — “UPDATE” button in header (local installs) Yes — “Check Now” button on a dedicated admin page
Update delivery method Self-upgrading binary/build git pull + dependency reinstall + frontend rebuild (update.sh), or container pull for Docker GitHub Releases API, downloaded and swapped atomically — the new version is fully downloaded before any file is replaced, so a failed or interrupted download can’t leave a half-updated, broken install
Auto-restart after update Not confirmed Depends on deployment — exits after update expecting a supervisor (systemd/pm2) to restart it; manual restart needed if run directly in a terminal Yes — automatic systemctl restart after a successful update, no supervisor setup required
Update history / audit trail No No Yes — dedicated admin page shows current version, last check time, and full update history

Satellites & orbital

Feature HamClock OpenHamClock Helioclock
Satellite pass prediction Yes (one at a time) Yes (40+ satellite catalog, SGP4 in-browser) Yes
ISS tracking Yes Yes Yes
Tiangong / CSS tracking No Not confirmed Planned

Weather, disaster & environmental data

Feature HamClock OpenHamClock Helioclock
Current conditions (temp/humidity/pressure) Yes Yes Yes
Radar (NEXRAD/precipitation) No Yes (precipitation overlay plugin) Yes — RainViewer + NOAA nowCOAST, plus a dedicated Radar Scope: circular proximity display centered on QTH or any zip/city, range rings, 8-direction nudge controls, live NWS alert polygons overlaid
Satellite cloud overlay (GOES) No No Yes
Lightning No No Yes (NOAA GOES GLM, live), plus a dedicated Lightning Scope — same circular proximity-display pattern as Radar Scope, strike rate/nearest-distance stats, proximity audio alert
Volcano activity No No Yes — VAAC advisories + USGS HANS, plus direct queries to individual national volcano observatories worldwide (concatenated in-house, not a licensed aggregator) and volcanic ash plume data
Earthquake activity No Yes (USGS overlay plugin) Yes (USGS layer) — both Helioclock and OpenHamClock have this, HamClock doesn’t
Maidenhead grid square overlay (visual grid lines on the map, not just text readout) No — grid square shown as text only Not confirmed as a map layer Yes — dedicated map layer
METAR aviation weather (station reports on the map) No No Yes — dedicated map layer, up to 50 user-selected stations; station search runs against an 8,509-station database bundled locally, no internet needed just to search
FAA aviation weather camera directory No No Yes — searchable directory of 955 FAA aviation weather camera sites (US, Alaska, Hawaii, Canada); selecting a site opens FAA’s own live camera page directly, no images fetched or hosted by Helioclock itself
Tropical storm / hurricane tracking No No Yes (JTWC)
Sea surface temp / anomaly No No Yes
Wildfire detection (NASA FIRMS) No No Yes, plus a dedicated Fire Scope — same proximity-scope pattern, requires a free NASA FIRMS API key
Air quality (AQI) No No Yes — EPA AirNow (North America) + WAQI (global fallback), both require free API keys
Tides No No Yes
UV index No No Yes
NWS weather alerts Not confirmed Yes (part of EmComm layout) Yes
FEMA disaster declarations No Yes (EmComm layout) No
EAS / IPAWS all-hazards alerts (AMBER, civil emergency) No Not built as such Planned
APRS emergency-comms dashboard (shelters, resource tracking, net check-ins) No Yes — dedicated EmComm layout for ARES/RACES/SKYWARN use In process

Deployment model

Feature HamClock OpenHamClock Helioclock
Configure your own hardware? Yes — flash OS, compile/select resolution, run installer Yes, for self-hosting (install Node.js, clone repo, edit .env) — or use their hosted openhamclock.com with zero setup, but that path depends entirely on their central server No — arrives preloaded on an SD card or USB stick for hardware you already own, or a turnkey appliance if you’d rather not. No Linux setup, and no dependency on any Helioclock-run central server either.
Turnkey pre-built device sold by the project itself No (third-party like Inovato Quadra exists, unofficial) No Yes — dedicated 1080p/4K appliance and multi-display server SKUs
Headless server + remote browser access Partial (“Live web” option on some builds) Yes, by design Yes, across every SKU — but every unit runs the same, supporting both local monitor(s) and Remote Browser View
Features for corporate/signage use (NOC, EOC, trading floor, lobby) No No Yes — explicit target market
Remote view via QR code No No Yes
Easy to load into your browser, no IP address to remember No — manual IP lookup (on-screen “LIP” readout or router DHCP table) No — manual IP lookup (hostname -I or router DHCP table); static IP reservation recommended for a permanent address Yes — helioclock.local via mDNS/avahi, no IP-hunting required

Other Helioclock-only features

Feature HamClock OpenHamClock Helioclock
World time zone map overlay Not confirmed as a map layer (DE/DX timezone shown as text, not a world map layer) Not confirmed Yes — confirmed: dedicated Timezone Boundaries layer
Seasonal base-map imagery (map imagery itself changes month to month — snow cover, vegetation, etc.) No — static base map imagery No — static map tiles Yes — 12 monthly Blue Marble images, swapped automatically on the 1st of each month
Interplanetary magnetic field plot (ACE satellite) alongside solar wind Not confirmed as a distinct plot Not built Yes — ACE IMF plot alongside solar wind density/speed
On-device shareable snapshot (QR code to a live screen capture, no phone camera needed) No No Yes — Alt+S triggers a screen capture, presented as a scannable QR code
Formal font/text contrast accessibility audit Not confirmed Not confirmed Yes — dedicated audit pass across the UI for text/background contrast
WWV/WWVH transmitter site map markers Not confirmed as distinct from NCDXF beacon markers Not confirmed Yes — on the Mercator and USA map views
Device system health monitoring (CPU, disk, memory, sensors) No No — OpenHamClock has a “Health Dashboard,” but it tracks server traffic/visitor analytics, not the device’s own hardware health, a different thing entirely Yes — dedicated Health Report panel, including NTP time-sync status
Device uptime display Yes — shown as a small corner readout Not confirmed Yes — dedicated Uptime Monitor MP/DP, plus mouseover with tooltips status bar display at the bottom
Configured city clocks shown as map markers (toggleable layer, not just a clock bar) No No Yes — confirmed: up to 6 configurable cities as a dedicated map layer
Air Quality, Tides, and UV Index as their own MP/DP panels No No Yes — Tides (NOAA CO-OPS, no API key) and UV Index (Open-Meteo, no API key) confirmed, alongside Air Quality
Persistent multi-event countdown timer (named events, e.g. next hamfest or contest, not just a single stopwatch/countdown mode) No — Big Clock has a single countdown mode, not multiple saved named events Not confirmed Yes — up to 10 named events tracked simultaneously, each with its own live countdown; a finished event stays visible marked STARTED for 24 hours before auto-clearing
Built-in ham radio desk reference No Not confirmed Yes — Quick Reference overlay (Alt+R): band plans by license class, antenna/RF formulas, Q-codes, phonetics and CW prosigns, coax loss tables, and a resistor/capacitor/connector reference, all one keystroke away
Automatic stall recovery (watchdog timer) No — known to require manual restarts if it crashes or hangs No Yes — a watchdog timer monitors the software and automatically recovers from any stall, no one has to notice and reboot it
Mouseover tooltips across the interface (map markers, panels, charts) Yes, in some contexts (setup field descriptions, DXPeditions list-to-map hover highlight) — not confirmed pervasive across the whole interface Not confirmed Yes — pervasive across map markers, panels, and sparkline/trend charts, not just markers
Interactive sparkline/trend charts with hover data tooltips Not confirmed Not confirmed — has 30-day history sparkline charts, but hover-tooltip behavior isn’t documented Yes

Hardware, rig control & extras

Feature HamClock OpenHamClock Helioclock
Rig/rotator control Yes (hamlib rotctld/rigctld) Yes, via companion “rig-bridge” service (also handles APRS TNC and Winlink) In process
PTT / “ON THE AIR” indicator Yes (GPIO) Not built Yes (GPIO or universal USB-serial adapter)
Native multi-monitor output (dedicated HDMI displays) No — requires a separate browser or device pointed at the HamClock web server for each additional screen No — same browser-server architecture; each screen needs its own device/browser session Yes — a single device drives 2-3 native HDMI outputs directly (Raspberry Pi 4/5: 2 outputs, N100/N150 mini PC: 2-3 outputs), no second computer or browser needed
CW practice/trainer No No Yes (physical key input via GPIO or USB code key)
Dedicated full-screen Big Clock (stopwatch/countdown/alarm modes) Yes No (has header clock + separate analog clock panel, not a unified full-screen mode) Yes, plus a stopwatch-first “Big Clock” full-screen mode, and a separate persistent Countdown Timer panel tracking up to 10 named events at once
Space-weather / band-open alert sounds Alarm only Yes — 9 selectable tones across 7 data feeds, configurable per-feed Yes — 9 alert categories, each with its own severity threshold and on/off toggle, step-up deduplication (won’t re-fire for the same event unless it escalates), plus a fully configurable news ticker with custom RSS/ATOM feed support and URL verification before saving
Financial markets panel No No Yes
SDR add-on (WWV/beacon direct-reception confirmation) No No Yes — optional add-on (RTL-SDR-based, purchased or owned separately)
Social media sharing (auto-post snapshots to Facebook, etc.) No No Planned
Shareable link for forum/community posting No No Planned

Sources

  • clearskyinstitute.com/ham/HamClock — original HamClock user guide (v2.70)
  • hamclock.com — community backend project
  • github.com/accius/openhamclock — OpenHamClock README, architecture docs, and API reference
  • QSO365, XARC, KD4C, LinuxLinks — independent HamClock reviews
  • Internal Helioclock changelogs (KA9NWM), current through v2.14.4 / server.js v2.4.1