diff --git a/packages/frontend/src/lib/query/client.ts b/packages/frontend/src/lib/query/client.ts
new file mode 100644
index 0000000..6f50228
--- /dev/null
+++ b/packages/frontend/src/lib/query/client.ts
@@ -0,0 +1,16 @@
+import { QueryClient } from "@tanstack/react-query";
+
+export const queryClient = new QueryClient({
+    defaultOptions: {
+        queries: {
+            staleTime: 5 * 60 * 1000, // 5 mins
+            gcTime: 10 * 60 * 1000, // 10 mins
+            retry: 1,
+            refetchOnWindowFocus: true,
+            refetchOnReconnect: true,
+        },
+        mutations: {
+            retry: 0,
+        },
+    },
+});
diff --git a/packages/frontend/src/lib/query/hooks/derived.ts b/packages/frontend/src/lib/query/hooks/derived.ts
new file mode 100644
index 0000000..b825165
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/derived.ts
@@ -0,0 +1,35 @@
+import { useMemo } from "react";
+import { useSelection } from "@/components/selection-provider";
+import { useIssues } from "@/lib/query/hooks/issues";
+import { useOrganisations } from "@/lib/query/hooks/organisations";
+import { useProjects } from "@/lib/query/hooks/projects";
+
+export function useSelectedOrganisation() {
+    const { selectedOrganisationId } = useSelection();
+    const { data: organisations = [] } = useOrganisations();
+
+    return useMemo(
+        () => organisations.find((org) => org.Organisation.id === selectedOrganisationId) ?? null,
+        [organisations, selectedOrganisationId],
+    );
+}
+
+export function useSelectedProject() {
+    const { selectedOrganisationId, selectedProjectId } = useSelection();
+    const { data: projects = [] } = useProjects(selectedOrganisationId);
+
+    return useMemo(
+        () => projects.find((project) => project.Project.id === selectedProjectId) ?? null,
+        [projects, selectedProjectId],
+    );
+}
+
+export function useSelectedIssue() {
+    const { selectedProjectId, selectedIssueId } = useSelection();
+    const { data: issues = [] } = useIssues(selectedProjectId);
+
+    return useMemo(
+        () => issues.find((issue) => issue.Issue.id === selectedIssueId) ?? null,
+        [issues, selectedIssueId],
+    );
+}
diff --git a/packages/frontend/src/lib/query/hooks/index.ts b/packages/frontend/src/lib/query/hooks/index.ts
new file mode 100644
index 0000000..b30da5b
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/index.ts
@@ -0,0 +1,7 @@
+export * from "@/lib/query/hooks/derived";
+export * from "@/lib/query/hooks/issues";
+export * from "@/lib/query/hooks/organisations";
+export * from "@/lib/query/hooks/projects";
+export * from "@/lib/query/hooks/sprints";
+export * from "@/lib/query/hooks/timers";
+export * from "@/lib/query/hooks/users";
diff --git a/packages/frontend/src/lib/query/hooks/issues.ts b/packages/frontend/src/lib/query/hooks/issues.ts
new file mode 100644
index 0000000..404581f
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/issues.ts
@@ -0,0 +1,78 @@
+import type {
+    IssueCreateRequest,
+    IssueRecord,
+    IssueResponse,
+    IssuesReplaceStatusRequest,
+    IssueUpdateRequest,
+    StatusCountResponse,
+    SuccessResponse,
+} from "@sprint/shared";
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { queryKeys } from "@/lib/query/keys";
+import { issue } from "@/lib/server";
+
+export function useIssues(projectId?: number | null) {
+    return useQuery<IssueResponse[]>({
+        queryKey: queryKeys.issues.byProject(projectId ?? 0),
+        queryFn: () => issue.byProject(projectId ?? 0),
+        enabled: Boolean(projectId),
+    });
+}
+
+export function useIssueStatusCount(organisationId?: number | null, status?: string | null) {
+    return useQuery<StatusCountResponse>({
+        queryKey: queryKeys.issues.statusCount(organisationId ?? 0, status ?? ""),
+        queryFn: () => issue.statusCount(organisationId ?? 0, status ?? ""),
+        enabled: Boolean(organisationId && status),
+    });
+}
+
+export function useCreateIssue() {
+    const queryClient = useQueryClient();
+
+    return useMutation<IssueRecord, Error, IssueCreateRequest>({
+        mutationKey: ["issues", "create"],
+        mutationFn: issue.create,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({
+                queryKey: queryKeys.issues.byProject(variables.projectId),
+            });
+        },
+    });
+}
+
+export function useUpdateIssue() {
+    const queryClient = useQueryClient();
+
+    return useMutation<IssueRecord, Error, IssueUpdateRequest>({
+        mutationKey: ["issues", "update"],
+        mutationFn: issue.update,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.issues.all });
+        },
+    });
+}
+
+export function useDeleteIssue() {
+    const queryClient = useQueryClient();
+
+    return useMutation<SuccessResponse, Error, number>({
+        mutationKey: ["issues", "delete"],
+        mutationFn: issue.delete,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.issues.all });
+        },
+    });
+}
+
+export function useReplaceIssueStatus() {
+    const queryClient = useQueryClient();
+
+    return useMutation<unknown, Error, IssuesReplaceStatusRequest>({
+        mutationKey: ["issues", "replace-status"],
+        mutationFn: issue.replaceStatus,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.issues.all });
+        },
+    });
+}
diff --git a/packages/frontend/src/lib/query/hooks/organisations.ts b/packages/frontend/src/lib/query/hooks/organisations.ts
new file mode 100644
index 0000000..412d3bb
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/organisations.ts
@@ -0,0 +1,101 @@
+import type {
+    OrgAddMemberRequest,
+    OrganisationMemberRecord,
+    OrganisationMemberResponse,
+} from "@sprint/shared";
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { queryKeys } from "@/lib/query/keys";
+import { organisation } from "@/lib/server";
+
+export function useOrganisations() {
+    return useQuery({
+        queryKey: queryKeys.organisations.byUser(),
+        queryFn: organisation.byUser,
+    });
+}
+
+export function useOrganisationMembers(organisationId?: number | null) {
+    return useQuery<OrganisationMemberResponse[]>({
+        queryKey: queryKeys.organisations.members(organisationId ?? 0),
+        queryFn: () => organisation.members(organisationId ?? 0),
+        enabled: Boolean(organisationId),
+    });
+}
+
+export function useCreateOrganisation() {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationKey: ["organisations", "create"],
+        mutationFn: organisation.create,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.organisations.byUser() });
+        },
+    });
+}
+
+export function useUpdateOrganisation() {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationKey: ["organisations", "update"],
+        mutationFn: organisation.update,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.organisations.byUser() });
+        },
+    });
+}
+
+export function useDeleteOrganisation() {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationKey: ["organisations", "delete"],
+        mutationFn: organisation.remove,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.organisations.byUser() });
+        },
+    });
+}
+
+export function useAddOrganisationMember() {
+    const queryClient = useQueryClient();
+
+    return useMutation<OrganisationMemberRecord, Error, OrgAddMemberRequest>({
+        mutationKey: ["organisations", "members", "add"],
+        mutationFn: organisation.addMember,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({
+                queryKey: queryKeys.organisations.members(variables.organisationId),
+            });
+        },
+    });
+}
+
+export function useRemoveOrganisationMember() {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationKey: ["organisations", "members", "remove"],
+        mutationFn: organisation.removeMember,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({
+                queryKey: queryKeys.organisations.members(variables.organisationId),
+            });
+        },
+    });
+}
+
+export function useUpdateOrganisationMemberRole() {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationKey: ["organisations", "members", "update-role"],
+        mutationFn: organisation.updateMemberRole,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({
+                queryKey: queryKeys.organisations.members(variables.organisationId),
+            });
+        },
+    });
+}
diff --git a/packages/frontend/src/lib/query/hooks/projects.ts b/packages/frontend/src/lib/query/hooks/projects.ts
new file mode 100644
index 0000000..eb30d64
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/projects.ts
@@ -0,0 +1,55 @@
+import type {
+    ProjectCreateRequest,
+    ProjectRecord,
+    ProjectResponse,
+    ProjectUpdateRequest,
+} from "@sprint/shared";
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { queryKeys } from "@/lib/query/keys";
+import { project } from "@/lib/server";
+
+export function useProjects(organisationId?: number | null) {
+    return useQuery<ProjectResponse[]>({
+        queryKey: queryKeys.projects.byOrganisation(organisationId ?? 0),
+        queryFn: () => project.byOrganisation(organisationId ?? 0),
+        enabled: Boolean(organisationId),
+    });
+}
+
+export function useCreateProject() {
+    const queryClient = useQueryClient();
+
+    return useMutation<ProjectRecord, Error, ProjectCreateRequest>({
+        mutationKey: ["projects", "create"],
+        mutationFn: project.create,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({
+                queryKey: queryKeys.projects.byOrganisation(variables.organisationId),
+            });
+        },
+    });
+}
+
+export function useUpdateProject() {
+    const queryClient = useQueryClient();
+
+    return useMutation<ProjectRecord, Error, ProjectUpdateRequest>({
+        mutationKey: ["projects", "update"],
+        mutationFn: project.update,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.projects.all });
+        },
+    });
+}
+
+export function useDeleteProject() {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationKey: ["projects", "delete"],
+        mutationFn: project.remove,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.projects.all });
+        },
+    });
+}
diff --git a/packages/frontend/src/lib/query/hooks/sprints.ts b/packages/frontend/src/lib/query/hooks/sprints.ts
new file mode 100644
index 0000000..14b432c
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/sprints.ts
@@ -0,0 +1,48 @@
+import type { SprintCreateRequest, SprintRecord, SprintUpdateRequest } from "@sprint/shared";
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { queryKeys } from "@/lib/query/keys";
+import { sprint } from "@/lib/server";
+
+export function useSprints(projectId?: number | null) {
+    return useQuery<SprintRecord[]>({
+        queryKey: queryKeys.sprints.byProject(projectId ?? 0),
+        queryFn: () => sprint.byProject(projectId ?? 0),
+        enabled: Boolean(projectId),
+    });
+}
+
+export function useCreateSprint() {
+    const queryClient = useQueryClient();
+
+    return useMutation<SprintRecord, Error, SprintCreateRequest>({
+        mutationKey: ["sprints", "create"],
+        mutationFn: sprint.create,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.sprints.byProject(variables.projectId) });
+        },
+    });
+}
+
+export function useUpdateSprint() {
+    const queryClient = useQueryClient();
+
+    return useMutation<SprintRecord, Error, SprintUpdateRequest>({
+        mutationKey: ["sprints", "update"],
+        mutationFn: sprint.update,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.sprints.all });
+        },
+    });
+}
+
+export function useDeleteSprint() {
+    const queryClient = useQueryClient();
+
+    return useMutation({
+        mutationKey: ["sprints", "delete"],
+        mutationFn: sprint.remove,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.sprints.all });
+        },
+    });
+}
diff --git a/packages/frontend/src/lib/query/hooks/timers.ts b/packages/frontend/src/lib/query/hooks/timers.ts
new file mode 100644
index 0000000..347794d
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/timers.ts
@@ -0,0 +1,50 @@
+import type { TimerEndRequest, TimerState, TimerToggleRequest } from "@sprint/shared";
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { queryKeys } from "@/lib/query/keys";
+import { timer } from "@/lib/server";
+
+export function useTimerState(issueId?: number | null, options?: { refetchInterval?: number }) {
+    return useQuery<TimerState>({
+        queryKey: queryKeys.timers.active(issueId ?? 0),
+        queryFn: () => timer.get(issueId ?? 0),
+        enabled: Boolean(issueId),
+        refetchInterval: options?.refetchInterval,
+        refetchIntervalInBackground: false,
+    });
+}
+
+export function useInactiveTimers(issueId?: number | null, options?: { refetchInterval?: number }) {
+    return useQuery<TimerState[]>({
+        queryKey: queryKeys.timers.inactive(issueId ?? 0),
+        queryFn: () => timer.getInactive(issueId ?? 0),
+        enabled: Boolean(issueId),
+        refetchInterval: options?.refetchInterval,
+        refetchIntervalInBackground: false,
+    });
+}
+
+export function useToggleTimer() {
+    const queryClient = useQueryClient();
+
+    return useMutation<TimerState, Error, TimerToggleRequest>({
+        mutationKey: ["timers", "toggle"],
+        mutationFn: timer.toggle,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.timers.active(variables.issueId) });
+            queryClient.invalidateQueries({ queryKey: queryKeys.timers.inactive(variables.issueId) });
+        },
+    });
+}
+
+export function useEndTimer() {
+    const queryClient = useQueryClient();
+
+    return useMutation<TimerState, Error, TimerEndRequest>({
+        mutationKey: ["timers", "end"],
+        mutationFn: timer.end,
+        onSuccess: (_data, variables) => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.timers.active(variables.issueId) });
+            queryClient.invalidateQueries({ queryKey: queryKeys.timers.inactive(variables.issueId) });
+        },
+    });
+}
diff --git a/packages/frontend/src/lib/query/hooks/users.ts b/packages/frontend/src/lib/query/hooks/users.ts
new file mode 100644
index 0000000..deefe87
--- /dev/null
+++ b/packages/frontend/src/lib/query/hooks/users.ts
@@ -0,0 +1,36 @@
+import type { UserRecord, UserUpdateRequest } from "@sprint/shared";
+import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
+import { queryKeys } from "@/lib/query/keys";
+import { user } from "@/lib/server";
+
+export function useUserByUsername(username?: string | null) {
+    return useQuery<UserRecord>({
+        queryKey: queryKeys.users.byUsername(username ?? ""),
+        queryFn: () => user.byUsername(username ?? ""),
+        enabled: Boolean(username),
+    });
+}
+
+export function useUpdateUser() {
+    const queryClient = useQueryClient();
+
+    return useMutation<UserRecord, Error, UserUpdateRequest>({
+        mutationKey: ["users", "update"],
+        mutationFn: user.update,
+        onSuccess: (_data) => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.users.all });
+        },
+    });
+}
+
+export function useUploadAvatar() {
+    const queryClient = useQueryClient();
+
+    return useMutation<string, Error, File>({
+        mutationKey: ["users", "upload-avatar"],
+        mutationFn: user.uploadAvatar,
+        onSuccess: () => {
+            queryClient.invalidateQueries({ queryKey: queryKeys.users.all });
+        },
+    });
+}
diff --git a/packages/frontend/src/lib/query/keys.ts b/packages/frontend/src/lib/query/keys.ts
new file mode 100644
index 0000000..1a05850
--- /dev/null
+++ b/packages/frontend/src/lib/query/keys.ts
@@ -0,0 +1,33 @@
+// query key factory for granular cache invalidation
+
+export const queryKeys = {
+    organisations: {
+        all: ["organisations"] as const,
+        byUser: () => [...queryKeys.organisations.all, "by-user"] as const,
+        members: (orgId: number) => [...queryKeys.organisations.all, orgId, "members"] as const,
+    },
+    projects: {
+        all: ["projects"] as const,
+        byOrganisation: (orgId: number) => [...queryKeys.projects.all, "by-org", orgId] as const,
+    },
+    issues: {
+        all: ["issues"] as const,
+        byProject: (projectId: number) => [...queryKeys.issues.all, "by-project", projectId] as const,
+        statusCount: (organisationId: number, status: string) =>
+            [...queryKeys.issues.all, "status-count", organisationId, status] as const,
+    },
+    sprints: {
+        all: ["sprints"] as const,
+        byProject: (projectId: number) => [...queryKeys.sprints.all, "by-project", projectId] as const,
+    },
+    timers: {
+        all: ["timers"] as const,
+        active: (issueId: number) => [...queryKeys.timers.all, "active", issueId] as const,
+        inactive: (issueId: number) => [...queryKeys.timers.all, "inactive", issueId] as const,
+        list: (issueId: number) => [...queryKeys.timers.all, "list", issueId] as const,
+    },
+    users: {
+        all: ["users"] as const,
+        byUsername: (username: string) => [...queryKeys.users.all, "by-username", username] as const,
+    },
+};