diff --git a/static/add_instance_flow.mts b/static/add_instance_flow.mts
index 6f22ae5..522a1cc 100644
--- a/static/add_instance_flow.mts
+++ b/static/add_instance_flow.mts
@@ -39,6 +39,7 @@ export class AddInstanceFlow {
             hostSecure: secure,
             software: "",
             iconURL: null,
+            preferredFor: []
         };
 
         try {
diff --git a/static/config.html b/static/config.html
index 6066eb4..ac206fb 100644
--- a/static/config.html
+++ b/static/config.html
@@ -101,9 +101,9 @@ Unchecking this is not recommended, and this option only exists for exceptional
             <br>
             <label for="defaultsList">Default option for:</label><br>
             <select id="defaultsList" class="full-width" multiple>
-                <option value="" disabled>(None, use the "Redirect always" button to set!)</option>
+                <option id="noDefaults" value="" disabled>(None, use the "Redirect always" button to set!)</option>
             </select>
-            <button id="removeDefaults" disabled>Remove</button>
+            <button id="removeDefaults" type="button" disabled>Remove</button>
             <br><br>
             <button type="submit">OK</button>
             <button type="reset" class="close">Cancel</button>
diff --git a/static/config.mts b/static/config.mts
index 6f807b2..86015d5 100644
--- a/static/config.mts
+++ b/static/config.mts
@@ -1,6 +1,5 @@
-import { parseHost } from "./add_an_instance.mjs";
 import { AddInstanceFlow } from "./add_instance_flow.mjs";
-import { dialogDetailsFromInstance, dialogDetailsToInstance, InstanceDetailsDialog, InstanceDetailsDialogData } from "./confirm_instance_details.mjs";
+import { dialogDetailsFromInstance, dialogDetailsToInstance, InstanceDetailsDialog } from "./confirm_instance_details.mjs";
 import { findButtonOrFail, findDialogOrFail, findOlOrFail } from "./dom.mjs";
 import storageManager, { Instance } from "./storage_manager.mjs";
 
diff --git a/static/confirm_instance_details.mts b/static/confirm_instance_details.mts
index 689877a..ff3a273 100644
--- a/static/confirm_instance_details.mts
+++ b/static/confirm_instance_details.mts
@@ -2,7 +2,7 @@
 
 import { parseHost } from "./add_an_instance.mjs";
 import { FormDialog, ONCE } from "./dialog.mjs";
-import { findButtonOrFail, findFormOrFail, findImageOrFail, findInputOrFail, findSelectOrFail } from "./dom.mjs";
+import { findButtonOrFail, findFormOrFail, findImageOrFail, findInputOrFail, findOptionOrFail, findSelectOrFail } from "./dom.mjs";
 import knownSoftware from "./known_software.mjs";
 import { Instance } from "./storage_manager.mjs";
 
@@ -17,7 +17,8 @@ export type InstanceDetailsDialogData = {
     host: string,
     hostSecure: boolean,
     software: string,
-    iconURL: string | null
+    iconURL: string | null,
+    preferredFor: string[],
 };
 
 export function dialogDetailsFromInstance(instance: Instance): InstanceDetailsDialogData {
@@ -27,7 +28,8 @@ export function dialogDetailsFromInstance(instance: Instance): InstanceDetailsDi
         host: host.host,
         hostSecure: host.secure,
         software: instance.software,
-        iconURL: instance.iconURL ?? null
+        iconURL: instance.iconURL ?? null,
+        preferredFor: instance.preferredFor,
     };
 }
 
@@ -36,6 +38,7 @@ export function dialogDetailsToInstance(data: InstanceDetailsDialogData, instanc
     instance.origin = mergeHost(data.host, data.hostSecure);
     instance.software = data.software;
     instance.iconURL = data.iconURL ?? undefined;
+    instance.preferredFor = data.preferredFor;
     return instance as Instance;
 }
 
@@ -46,6 +49,11 @@ export class InstanceDetailsDialog extends FormDialog {
     protected instanceSoftware: HTMLSelectElement;
     protected instanceIcon: HTMLImageElement;
     protected closeButton: HTMLButtonElement;
+    protected defaultsList?: {
+        list: HTMLSelectElement,
+        removeButton: HTMLButtonElement,
+        noDefaultsOption: HTMLOptionElement,
+    };
 
     constructor(dialog: HTMLDialogElement, initializeDOM: boolean = true) {
         super(dialog, findFormOrFail(dialog, ".instanceDetailsForm"));
@@ -56,6 +64,15 @@ export class InstanceDetailsDialog extends FormDialog {
         this.instanceSoftware = findSelectOrFail(this.form, "#instanceSoftware");
         this.instanceIcon = findImageOrFail(this.form, "#instanceIcon");
         this.closeButton = findButtonOrFail(this.form, ".close");
+        try {
+            this.defaultsList = {
+                list: findSelectOrFail(this.form, "#defaultsList"),
+                removeButton: findButtonOrFail(this.form, "#removeDefaults"),
+                noDefaultsOption: findOptionOrFail(this.form, "#noDefaults"),
+            };
+        } catch {
+            this.defaultsList = undefined;
+        }
 
         if (initializeDOM) this.initializeDOM();
     }
@@ -71,6 +88,70 @@ export class InstanceDetailsDialog extends FormDialog {
         this.instanceIcon.src = blankImage;
 
         this.closeButton.addEventListener("click", e => this.close());
+
+        if (this.defaultsList) {
+            this.defaultsList.list.addEventListener("change", e => this.#handleListSelectionChange());
+            this.defaultsList.removeButton.addEventListener("click", e => this.#removeSelectedListOptions());
+        }
+    }
+
+    #getRemainingListOptions(): string[] {
+        if (!this.defaultsList) return [];
+
+        const items: string[] = [];
+
+        for (const option of this.defaultsList.list.options) {
+            if (option == this.defaultsList.noDefaultsOption) continue;
+            items.push(option.value);
+        }
+
+        return items;
+    }
+
+    #removeSelectedListOptions() {
+        if (!this.defaultsList) return;
+
+        // Copy using spread because this breaks when the list changes mid-iteration
+        for (const option of [...this.defaultsList.list.selectedOptions]) {
+            option.remove();
+        }
+
+        this.#handleListChange();
+    }
+
+    #populateDefaultsList(items: string[]) {
+        if (!this.defaultsList) return;
+
+        while (this.defaultsList.list.children.length > 1)
+            this.defaultsList.list.removeChild(this.defaultsList.list.lastChild!);
+
+        for (const item of items) {
+            const option = document.createElement("option");
+            option.value = item;
+            option.innerText = knownSoftware.software[item]?.name ?? knownSoftware.groups[item]?.name ?? item;
+            this.defaultsList.list.appendChild(option);
+        }
+
+        this.#handleListChange();
+    }
+
+    #handleListChange() {
+        this.#handleListEmpty();
+        this.#handleListSelectionChange();
+    }
+
+    #handleListSelectionChange() {
+        if (!this.defaultsList) return;
+        this.defaultsList.removeButton.disabled = this.defaultsList.list.selectedOptions.length === 0;
+    }
+
+    #handleListEmpty() {
+        if (!this.defaultsList) return;
+        if (this.defaultsList.list.children.length == 1) {
+            this.defaultsList.noDefaultsOption.removeAttribute("hidden");
+        } else {
+            this.defaultsList.noDefaultsOption.setAttribute("hidden", "");
+        }
     }
 
     #handleSubmit(data: InstanceDetailsDialogData, resolve: (data: InstanceDetailsDialogData) => void) {
@@ -79,6 +160,7 @@ export class InstanceDetailsDialog extends FormDialog {
             data.host = this.instanceHost.value;
             data.hostSecure = this.instanceHostSecure.checked;
             data.software = this.instanceSoftware.value;
+            data.preferredFor = this.#getRemainingListOptions();
 
             resolve(data);
             this.close();
@@ -91,6 +173,7 @@ export class InstanceDetailsDialog extends FormDialog {
         this.instanceHostSecure.checked = data.hostSecure;
         this.instanceSoftware.value = data.software;
         this.instanceIcon.src = data.iconURL ?? blankImage;
+        this.#populateDefaultsList(data.preferredFor);
 
         return new Promise((resolve, reject) => {
             this.cancelOnceClosed(reject);
diff --git a/static/dom.mts b/static/dom.mts
index 2c4267c..b0ec231 100644
--- a/static/dom.mts
+++ b/static/dom.mts
@@ -1,6 +1,13 @@
 // I would've LOVED to use generics for this but unfortunately that's not possible.
 // Type safety, but at what cost... >~< thanks TypeScript
 
+export function findOptionOrFail(on: Element, selector: string): HTMLOptionElement {
+    const element = on.querySelector(selector);
+    if (!(element instanceof HTMLOptionElement))
+        throw new Error(`${selector} isn't an option`);
+    return element;
+}
+
 export function findOlOrFail(on: Element, selector: string): HTMLOListElement {
     const element = on.querySelector(selector);
     if (!(element instanceof HTMLOListElement))