diff --git a/gerbil-manager-web/src/api/client.ts b/gerbil-manager-web/src/api/client.ts
index d3751c5..c9cfbca 100644
--- a/gerbil-manager-web/src/api/client.ts
+++ b/gerbil-manager-web/src/api/client.ts
@@ -62,5 +62,7 @@ export const api = {
 export const resources = {
   gerbils: '/gerbils',
   litters: '/litters',
-  breeders: '/breeders',
+  contacts: '/contacts',
+  enclosures: '/enclosures',
+  colorVarieties: '/color-varieties',
 } as const
diff --git a/gerbil-manager-web/src/api/gerbils.ts b/gerbil-manager-web/src/api/gerbils.ts
new file mode 100644
index 0000000..184bbc4
--- /dev/null
+++ b/gerbil-manager-web/src/api/gerbils.ts
@@ -0,0 +1,24 @@
+/** Typed API functions for the Tiere (Rennmäuse) resource. */
+import { api, resources } from './client'
+import { toQueryString, type GridifyQuery } from './gridify'
+import type { CreateGerbil, Gerbil, Paged, UpdateGerbil } from './types'
+
+export function listGerbils(query: GridifyQuery): Promise<Paged<Gerbil>> {
+  return api.get<Paged<Gerbil>>(`${resources.gerbils}${toQueryString(query)}`)
+}
+
+export function getGerbil(id: string): Promise<Gerbil> {
+  return api.get<Gerbil>(`${resources.gerbils}/${id}`)
+}
+
+export function createGerbil(body: CreateGerbil): Promise<Gerbil> {
+  return api.post<Gerbil>(resources.gerbils, body)
+}
+
+export function updateGerbil(id: string, body: UpdateGerbil): Promise<Gerbil> {
+  return api.put<Gerbil>(`${resources.gerbils}/${id}`, body)
+}
+
+export function deleteGerbil(id: string): Promise<void> {
+  return api.delete(`${resources.gerbils}/${id}`)
+}
diff --git a/gerbil-manager-web/src/api/lookups.ts b/gerbil-manager-web/src/api/lookups.ts
new file mode 100644
index 0000000..ebed7df
--- /dev/null
+++ b/gerbil-manager-web/src/api/lookups.ts
@@ -0,0 +1,34 @@
+/**
+ * Lookup resources used to populate form dropdowns (Farbschlag, Becken,
+ * Kontakte, Würfe). These endpoints are Gridify-paged like the rest; for
+ * dropdowns we request a large page and read `.items`.
+ */
+import { api, resources } from './client'
+import { toQueryString } from './gridify'
+import type { ColorVariety, Contact, Enclosure, Litter, Paged } from './types'
+
+const ALL = toQueryString({ page: 1, pageSize: 1000, orderBy: 'name' })
+
+export async function listColorVarieties(): Promise<ColorVariety[]> {
+  const paged = await api.get<Paged<ColorVariety>>(
+    `${resources.colorVarieties}${toQueryString({ page: 1, pageSize: 1000, orderBy: 'sortOrder' })}`,
+  )
+  return paged.items
+}
+
+export async function listEnclosures(): Promise<Enclosure[]> {
+  const paged = await api.get<Paged<Enclosure>>(`${resources.enclosures}${ALL}`)
+  return paged.items
+}
+
+export async function listContacts(): Promise<Contact[]> {
+  const paged = await api.get<Paged<Contact>>(`${resources.contacts}${ALL}`)
+  return paged.items
+}
+
+export async function listLitters(): Promise<Litter[]> {
+  const paged = await api.get<Paged<Litter>>(
+    `${resources.litters}${toQueryString({ page: 1, pageSize: 1000, orderBy: 'date desc' })}`,
+  )
+  return paged.items
+}
diff --git a/gerbil-manager-web/src/hooks/useApi.ts b/gerbil-manager-web/src/hooks/useApi.ts
new file mode 100644
index 0000000..01c635b
--- /dev/null
+++ b/gerbil-manager-web/src/hooks/useApi.ts
@@ -0,0 +1,98 @@
+/**
+ * Minimal async-data hooks (no react-query dependency).
+ *
+ * `useApi` runs an async loader and tracks loading/error/data, re-running when
+ * `deps` change. `reload()` re-fetches on demand (e.g. after a mutation).
+ *
+ * Design notes (to satisfy the strict react-hooks rules):
+ *  - `loading` is DERIVED (resolved-key !== current-request-key), never set
+ *    synchronously inside the effect.
+ *  - the loader is read through a ref so the effect can key purely on the
+ *    request signature without re-running on every render.
+ */
+import { useCallback, useEffect, useRef, useState } from 'react'
+import { ApiError } from '../api/client'
+import { de } from '../strings/de'
+
+export interface AsyncState<T> {
+  data: T | null
+  loading: boolean
+  error: string | null
+  reload: () => void
+}
+
+function messageFor(err: unknown): string {
+  if (err instanceof ApiError) return err.message
+  if (err instanceof Error && err.message) return err.message
+  return de.api.errors.unknown
+}
+
+interface Resolved<T> {
+  key: string | null
+  data: T | null
+  error: string | null
+}
+
+export function useApi<T>(loader: () => Promise<T>, deps: unknown[]): AsyncState<T> {
+  const loaderRef = useRef(loader)
+  // Keep the loader ref current (declared before the request effect so it is
+  // synced first within a commit). Writing refs in render is disallowed.
+  useEffect(() => {
+    loaderRef.current = loader
+  })
+
+  const [nonce, setNonce] = useState(0)
+  const requestKey = `${nonce}:${JSON.stringify(deps)}`
+
+  const [resolved, setResolved] = useState<Resolved<T>>({ key: null, data: null, error: null })
+
+  useEffect(() => {
+    let cancelled = false
+    loaderRef
+      .current()
+      .then((result) => {
+        if (!cancelled) setResolved({ key: requestKey, data: result, error: null })
+      })
+      .catch((err) => {
+        if (!cancelled) setResolved({ key: requestKey, data: null, error: messageFor(err) })
+      })
+    return () => {
+      cancelled = true
+    }
+  }, [requestKey])
+
+  const reload = useCallback(() => setNonce((n) => n + 1), [])
+  const loading = resolved.key !== requestKey
+
+  return { data: resolved.data, loading, error: loading ? null : resolved.error, reload }
+}
+
+/** Wraps a mutation (create/update/delete) with pending + error state. */
+export function useMutation<TArgs extends unknown[], TResult>(
+  mutator: (...args: TArgs) => Promise<TResult>,
+): {
+  run: (...args: TArgs) => Promise<TResult>
+  pending: boolean
+  error: string | null
+} {
+  const [pending, setPending] = useState(false)
+  const [error, setError] = useState<string | null>(null)
+
+  const run = useCallback(
+    async (...args: TArgs) => {
+      setPending(true)
+      setError(null)
+      try {
+        return await mutator(...args)
+      } catch (err) {
+        setError(messageFor(err))
+        throw err
+      } finally {
+        setPending(false)
+      }
+    },
+    [mutator],
+  )
+
+  return { run, pending, error }
+}