Firmware mods for the Pioneer CDJ-900NXS. We took the player's firmware apart in an emulator and added what newer Pioneer players have: hot cues on the deck, beat jump, colour and 3-band waveforms, keys in Camelot colours and more.
Pick the mods you want in the builder. It patches the official 1.31 update in your browser and gives you a normal C900NXS.UPD to install like any update. The boot loader is never touched, so you can always go back to stock.
Build it in your browser
The builder takes the official 1.31 update and adds the mods you tick, on your computer. Only the main application changes; the boot loader and recovery are copied byte for byte and checked.
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+
Prefer the command line? The Python patcher builds the same file, byte for byte:
# pick the mods in a list
$ python cdj900nxs_patcher.py C900NXS.UPD
diff --git a/style.css b/style.css
index 277dea1..5daff37 100644
--- a/style.css
+++ b/style.css
@@ -492,6 +492,26 @@ h2.section-title { text-transform: uppercase; letter-spacing: .02em; }
@media (max-width: 560px) {
.tabs a { padding: 10px 7px 8px; letter-spacing: .06em; font-size: .72rem; }
}
+/* PLAY/PAUSE key inside the builder button: a round key with a green ring
+ that blinks like the player's when it waits; steady green on hover */
+.btn.play { padding: 7px 20px 7px 7px; gap: 12px; }
+.play-key {
+ width: 34px; height: 34px; border-radius: 50%; flex: none; display: grid; place-items: center;
+ background: radial-gradient(circle at 50% 35%, #2a2d33, #121418 70%);
+ box-shadow: inset 0 1px 0 rgba(255,255,255,.12), 0 1px 2px rgba(0,0,0,.5);
+ position: relative;
+}
+.play-key::before {
+ content: ""; position: absolute; inset: 2px; border-radius: 50%;
+ border: 2px solid var(--lcd-green); box-shadow: 0 0 8px var(--lcd-green), inset 0 0 6px color-mix(in srgb, var(--lcd-green) 50%, transparent);
+ animation: play-blink 1s steps(1, end) infinite;
+}
+.play-key svg { width: 17px; height: 10px; fill: #e8eaee; }
+.btn.play:hover .play-key::before { animation: none; opacity: 1; }
+@keyframes play-blink { 0% { opacity: 1; } 50% { opacity: .12; } }
+:root[data-theme="light"] .play-key::before { border-color: #8dffb4; box-shadow: 0 0 8px #8dffb4; }
+
@media (prefers-reduced-motion: reduce) {
.brand .disc { animation: none; }
+ .play-key::before { animation: none; }
}
diff --git a/tools/changelog.json b/tools/changelog.json
index f926e82..1c19086 100644
--- a/tools/changelog.json
+++ b/tools/changelog.json
@@ -1,6 +1,13 @@
{
"_about": "The site's changelog, newest first. Versions follow Semantic Versioning (MAJOR.MINOR.PATCH), dates ISO 8601 (DIN EN 28601). make_builder_data.py adds every mod's current version from its module and writes assets/versions.js.",
"site": [
+ {
+ "version": "1.4.1",
+ "date": "2026-10-20",
+ "changes": [
+ "Open the builder carries a PLAY/PAUSE key that blinks green like the player's."
+ ]
+ },
{
"version": "1.4.0",
"date": "2026-10-20",
diff --git a/upcoming.html b/upcoming.html
index ce90ae6..dca877b 100644
--- a/upcoming.html
+++ b/upcoming.html
@@ -8,9 +8,9 @@