diff --git a/src/lib/types/api/entities.ts b/src/lib/types/api/entities.ts
new file mode 100644
index 00000000..062cecef
--- /dev/null
+++ b/src/lib/types/api/entities.ts
@@ -0,0 +1,174 @@
+// Core entity types based on Rails blueprints
+// These are the base types for game objects
+
+export interface LocalizedName {
+  en: string
+  ja: string
+}
+
+// Weapon entity from WeaponBlueprint
+export interface Weapon {
+  id: string
+  granblueId: string
+  name: LocalizedName
+  element: number
+  proficiency: number
+  rarity: number
+  maxLevel: number
+  maxSkillLevel: number
+  maxAwakeningLevel: number
+  series: number
+  ax: boolean
+  axType: number
+  hp: {
+    minHp: number
+    maxHp: number
+    maxHpFlb: number
+    maxHpUlb: number
+  }
+  atk: {
+    minAtk: number
+    maxAtk: number
+    maxAtkFlb: number
+    maxAtkUlb: number
+  }
+  uncap: {
+    flb: boolean
+    ulb: boolean
+    transcendence: boolean
+  }
+}
+
+// Character entity from CharacterBlueprint
+export interface Character {
+  id: string
+  granblueId: string
+  name: LocalizedName
+  element: number
+  rarity: number
+  maxLevel: number
+  flb: boolean
+  ulb: boolean
+  transcendence: boolean
+  special: boolean
+  recruits: string | null
+}
+
+// Summon entity from SummonBlueprint
+export interface Summon {
+  id: string
+  granblueId: string
+  name: LocalizedName
+  element: number
+  rarity: number
+  maxLevel: number
+  flb: boolean
+  ulb: boolean
+  transcendence: boolean
+  subaura: boolean
+  hp: {
+    minHp: number
+    maxHp: number
+    maxHpFlb: number
+    maxHpUlb: number
+  }
+  atk: {
+    minAtk: number
+    maxAtk: number
+    maxAtkFlb: number
+    maxAtkUlb: number
+  }
+}
+
+// Job entity from JobBlueprint
+export interface Job {
+  id: string
+  granblueId: string
+  name: LocalizedName
+  row: number
+  order: number
+  proficiency: [number, number]
+  masterLevel?: number
+  ultimateMastery?: number
+  accessory?: boolean
+  accessoryType?: number
+}
+
+// JobSkill entity
+export interface JobSkill {
+  id: string
+  name: LocalizedName
+  slug: string
+  category: number
+  main: boolean
+  sub: boolean
+}
+
+// JobAccessory entity
+export interface JobAccessory {
+  id: string
+  name: LocalizedName
+  slug: string
+  granblueId: string
+}
+
+// Raid entity from RaidBlueprint
+export interface Raid {
+  id: string
+  slug: string
+  name: LocalizedName
+  level: number
+  element: number
+  group?: RaidGroup
+}
+
+// RaidGroup entity from RaidGroupBlueprint
+export interface RaidGroup {
+  id: string
+  name: LocalizedName
+  section: string
+  order: number
+  difficulty: number
+  hl: boolean
+  extra: boolean
+  guidebooks: boolean
+}
+
+// Awakening entity
+export interface Awakening {
+  id: string
+  name: LocalizedName
+  slug: string
+}
+
+// WeaponKey entity
+export interface WeaponKey {
+  id: string
+  name: LocalizedName
+  slug: string
+  keyType: string
+  slot: number
+}
+
+// SimpleAxSkill for weapon AX skills
+export interface SimpleAxSkill {
+  modifier: number
+  strength: number
+}
+
+// Guidebook entity
+export interface Guidebook {
+  id: string
+  name: LocalizedName
+  slug: string
+}
+
+// User entity
+export interface User {
+  id: string
+  username: string
+  profilePicture?: string
+  role?: string
+  createdAt?: string
+  updatedAt?: string
+}
\ No newline at end of file
diff --git a/src/lib/types/api/party.ts b/src/lib/types/api/party.ts
new file mode 100644
index 00000000..4983bef8
--- /dev/null
+++ b/src/lib/types/api/party.ts
@@ -0,0 +1,168 @@
+// Party and Grid types based on Rails blueprints
+// These define the party composition structure
+
+import type {
+  Weapon,
+  Character,
+  Summon,
+  Job,
+  JobSkill,
+  JobAccessory,
+  Raid,
+  Guidebook,
+  User,
+  Awakening,
+  WeaponKey,
+  SimpleAxSkill
+} from './entities'
+
+// Grid item types - these are the junction tables between Party and entities
+
+// GridWeapon from GridWeaponBlueprint
+export interface GridWeapon {
+  id: string
+  position: number
+  mainhand?: boolean
+  uncapLevel?: number
+  transcendenceStep?: number
+  element?: number
+  weapon: Weapon  // Named properly, not "object"
+  weaponKeys?: WeaponKey[]
+  ax?: SimpleAxSkill[]
+  awakening?: {
+    type: Awakening
+    level: number
+  }
+}
+
+// GridCharacter from GridCharacterBlueprint
+export interface GridCharacter {
+  id: string
+  position: number
+  uncapLevel?: number
+  perpetuity?: boolean
+  transcendenceStep?: number
+  character: Character  // Named properly, not "object"
+  awakening?: Awakening
+  rings?: Array<{ modifier: number; strength: number }>
+  earring?: { modifier: number; strength: number }
+  aetherial_mastery?: { modifier: number; strength: number }
+  over_mastery?: Array<{ modifier: number; strength: number }>
+}
+
+// GridSummon from GridSummonBlueprint
+export interface GridSummon {
+  id: string
+  position: number
+  main?: boolean
+  friend?: boolean
+  quickSummon?: boolean
+  uncapLevel?: number
+  transcendenceStep?: number
+  summon: Summon  // Named properly, not "object"
+}
+
+// JobSkillList for party job skills
+export interface JobSkillList {
+  0?: JobSkill
+  1?: JobSkill
+  2?: JobSkill
+  3?: JobSkill
+}
+
+// GuidebookList for party guidebooks
+export interface GuidebookList {
+  0?: Guidebook
+  1?: Guidebook
+  2?: Guidebook
+}
+
+// Party from PartyBlueprint
+export interface Party {
+  id: string
+  shortcode: string
+  name?: string
+  description?: string
+  fullAuto?: boolean
+  autoGuard?: boolean
+  autoSummon?: boolean
+  chargeAttack?: boolean
+  clearTime?: number
+  buttonCount?: number
+  turnCount?: number
+  chainCount?: number
+  visibility?: number
+  favorited?: boolean
+  extra?: boolean
+  remix?: boolean
+
+  // Relationships
+  weapons: GridWeapon[]
+  characters: GridCharacter[]
+  summons: GridSummon[]
+  job?: Job
+  jobSkills?: JobSkillList
+  accessory?: JobAccessory
+  raid?: Raid
+  guidebooks?: GuidebookList
+  user?: User
+  sourceParty?: Party
+  remixes?: Party[]
+
+  // Local client state
+  localId?: string
+
+  // Timestamps
+  createdAt?: string
+  updatedAt?: string
+}
+
+// Minimal party for list views
+export interface PartyPreview {
+  id: string
+  shortcode: string
+  name?: string
+  favorited?: boolean
+  visibility?: number
+  raid?: {
+    name: { en: string; ja: string }
+    group?: {
+      difficulty?: number
+      extra?: boolean
+      guidebooks?: boolean
+    }
+  }
+  job?: {
+    name: { en: string; ja: string }
+  }
+  weapons: Array<{
+    position: number
+    mainhand?: boolean
+    weapon: {
+      granblueId: number
+      name?: { en: string; ja: string }
+    }
+  }>
+  characters: Array<{
+    position: number
+    character: {
+      granblueId: number
+      name?: { en: string; ja: string }
+    }
+  }>
+  summons: Array<{
+    position: number
+    main?: boolean
+    friend?: boolean
+    summon: {
+      granblueId: number
+      name?: { en: string; ja: string }
+    }
+  }>
+  user?: {
+    id: string
+    username: string
+  }
+  createdAt?: string
+  updatedAt?: string
+}
\ No newline at end of file