diff --git a/src/controllers/api/crewShipFusionController.ts b/src/controllers/api/crewShipFusionController.ts
new file mode 100644
index 00000000..87cfd2ce
--- /dev/null
+++ b/src/controllers/api/crewShipFusionController.ts
@@ -0,0 +1,107 @@
+import { getJSONfromString } from "@/src/helpers/stringHelpers";
+import { addMiscItems, freeUpSlot, getInventory, updateCurrency } from "@/src/services/inventoryService";
+import { getAccountIdForRequest } from "@/src/services/loginService";
+import { IOid } from "@/src/types/commonTypes";
+import { ICrewShipComponentFingerprint, InventorySlot } from "@/src/types/inventoryTypes/inventoryTypes";
+import { IInventoryChanges } from "@/src/types/purchaseTypes";
+import { RequestHandler } from "express";
+import { ExportCustoms, ExportDojoRecipes } from "warframe-public-export-plus";
+
+export const crewShipFusionController: RequestHandler = async (req, res) => {
+    const accountId = await getAccountIdForRequest(req);
+    const inventory = await getInventory(accountId);
+    const payload = getJSONfromString<ICrewShipFusionRequest>(String(req.body));
+
+    const isWeapon = inventory.CrewShipWeapons.id(payload.PartA.$oid);
+    const itemA = isWeapon ?? inventory.CrewShipWeaponSkins.id(payload.PartA.$oid)!;
+    const category = isWeapon ? "CrewShipWeapons" : "CrewShipWeaponSkins";
+    const salvageCategory = isWeapon ? "CrewShipSalvagedWeapons" : "CrewShipSalvagedWeaponSkins";
+    const itemB = inventory[payload.SourceRecipe ? salvageCategory : category].id(payload.PartB.$oid)!;
+    const tierA = itemA.ItemType.charCodeAt(itemA.ItemType.length - 1) - 65;
+    const tierB = itemB.ItemType.charCodeAt(itemB.ItemType.length - 1) - 65;
+
+    const inventoryChanges: IInventoryChanges = {};
+
+    // Charge partial repair cost if fusing with an identified but unrepaired part
+    if (payload.SourceRecipe) {
+        const recipe = ExportDojoRecipes.research[payload.SourceRecipe];
+        updateCurrency(inventory, Math.round(recipe.price * 0.4), false, inventoryChanges);
+        const miscItemChanges = recipe.ingredients.map(x => ({ ...x, ItemCount: Math.round(x.ItemCount * -0.4) }));
+        addMiscItems(inventory, miscItemChanges);
+        inventoryChanges.MiscItems = miscItemChanges;
+    }
+
+    // Remove inferior item
+    if (payload.SourceRecipe) {
+        inventory[salvageCategory].pull({ _id: payload.PartB.$oid });
+        inventoryChanges.RemovedIdItems = [{ ItemId: payload.PartB }];
+    } else {
+        const inferiorId = tierA < tierB ? payload.PartA : payload.PartB;
+        inventory[category].pull({ _id: inferiorId.$oid });
+        inventoryChanges.RemovedIdItems = [{ ItemId: inferiorId }];
+        freeUpSlot(inventory, InventorySlot.RJ_COMPONENT_AND_ARMAMENTS);
+        inventoryChanges[InventorySlot.RJ_COMPONENT_AND_ARMAMENTS] = { count: -1, platinum: 0, Slots: 1 };
+    }
+
+    // Upgrade superior item
+    const superiorItem = tierA < tierB ? itemB : itemA;
+    const inferiorItem = tierA < tierB ? itemA : itemB;
+    const fingerprint: ICrewShipComponentFingerprint = JSON.parse(
+        superiorItem.UpgradeFingerprint!
+    ) as ICrewShipComponentFingerprint;
+    const inferiorFingerprint: ICrewShipComponentFingerprint = inferiorItem.UpgradeFingerprint
+        ? (JSON.parse(inferiorItem.UpgradeFingerprint) as ICrewShipComponentFingerprint)
+        : { compat: "", buffs: [] };
+    if (isWeapon) {
+        for (let i = 0; i != fingerprint.buffs.length; ++i) {
+            const buffA = fingerprint.buffs[i];
+            const buffB = i < inferiorFingerprint.buffs.length ? inferiorFingerprint.buffs[i] : undefined;
+            const fvalA = buffA.Value / 0x3fffffff;
+            const fvalB = (buffB?.Value ?? 0) / 0x3fffffff;
+            const percA = 0.3 + fvalA * (0.6 - 0.3);
+            const percB = 0.3 + fvalB * (0.6 - 0.3);
+            const newPerc = Math.min(0.6, Math.max(percA, percB) * FUSE_MULTIPLIERS[Math.abs(tierA - tierB)]);
+            const newFval = (newPerc - 0.3) / (0.6 - 0.3);
+            buffA.Value = Math.trunc(newFval * 0x3fffffff);
+        }
+    } else {
+        const superiorMeta = ExportCustoms[superiorItem.ItemType].randomisedUpgrades ?? [];
+        const inferiorMeta = ExportCustoms[inferiorItem.ItemType].randomisedUpgrades ?? [];
+        for (let i = 0; i != inferiorFingerprint.buffs.length; ++i) {
+            const buffA = fingerprint.buffs[i];
+            const buffB = inferiorFingerprint.buffs[i];
+            const fvalA = buffA.Value / 0x3fffffff;
+            const fvalB = buffB.Value / 0x3fffffff;
+            const rangeA = superiorMeta[i].range;
+            const rangeB = inferiorMeta[i].range;
+            const percA = rangeA[0] + fvalA * (rangeA[1] - rangeA[0]);
+            const percB = rangeB[0] + fvalB * (rangeB[1] - rangeB[0]);
+            const newPerc = Math.min(rangeA[1], Math.max(percA, percB) * FUSE_MULTIPLIERS[Math.abs(tierA - tierB)]);
+            const newFval = (newPerc - rangeA[0]) / (rangeA[1] - rangeA[0]);
+            buffA.Value = Math.trunc(newFval * 0x3fffffff);
+        }
+        if (inferiorFingerprint.SubroutineIndex) {
+            const useSuperiorSubroutine = tierA < tierB ? !payload.UseSubroutineA : payload.UseSubroutineA;
+            if (!useSuperiorSubroutine) {
+                fingerprint.SubroutineIndex = inferiorFingerprint.SubroutineIndex;
+            }
+        }
+    }
+    superiorItem.UpgradeFingerprint = JSON.stringify(fingerprint);
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    inventoryChanges[category] = [superiorItem.toJSON() as any];
+
+    await inventory.save();
+    res.json({
+        InventoryChanges: inventoryChanges
+    });
+};
+
+interface ICrewShipFusionRequest {
+    PartA: IOid;
+    PartB: IOid;
+    SourceRecipe: string;
+    UseSubroutineA: boolean;
+}
+
+const FUSE_MULTIPLIERS = [1.1, 1.05, 1.02];
diff --git a/src/routes/api.ts b/src/routes/api.ts
index 8b0a12bc..df9e8b59 100644
--- a/src/routes/api.ts
+++ b/src/routes/api.ts
@@ -33,6 +33,7 @@ import { createAllianceController } from "@/src/controllers/api/createAllianceCo
 import { createGuildController } from "@/src/controllers/api/createGuildController";
 import { creditsController } from "@/src/controllers/api/creditsController";
 import { crewMembersController } from "@/src/controllers/api/crewMembersController";
+import { crewShipFusionController } from "@/src/controllers/api/crewShipFusionController";
 import { crewShipIdentifySalvageController } from "@/src/controllers/api/crewShipIdentifySalvageController";
 import { customizeGuildRanksController } from "@/src/controllers/api/customizeGuildRanksController";
 import { customObstacleCourseLeaderboardController } from "@/src/controllers/api/customObstacleCourseLeaderboardController";
@@ -247,6 +248,7 @@ apiRouter.post("/contributeToVault.php", contributeToVaultController);
 apiRouter.post("/createAlliance.php", createAllianceController);
 apiRouter.post("/createGuild.php", createGuildController);
 apiRouter.post("/crewMembers.php", crewMembersController);
+apiRouter.post("/crewShipFusion.php", crewShipFusionController);
 apiRouter.post("/crewShipIdentifySalvage.php", crewShipIdentifySalvageController);
 apiRouter.post("/customizeGuildRanks.php", customizeGuildRanksController);
 apiRouter.post("/customObstacleCourseLeaderboard.php", customObstacleCourseLeaderboardController);