diff --git a/.gitignore b/.gitignore
index c9089f1b9..60adfca77 100644
--- a/.gitignore
+++ b/.gitignore
@@ -48,5 +48,6 @@ devenv.local.nix
 # AI Tools
 /.claude/settings.local.json
 PLAN.md
+plans/
 /.crush/
 /.playwright-mcp
diff --git a/frontend/src/i18n/lang/en.json b/frontend/src/i18n/lang/en.json
index 3d4b43c12..c65726dd9 100644
--- a/frontend/src/i18n/lang/en.json
+++ b/frontend/src/i18n/lang/en.json
@@ -212,11 +212,16 @@
           "text1": "Are you sure you want to delete the token \"{token}\"?",
           "text2": "This will revoke access to all applications or integrations using it. You cannot undo this."
         },
+        "projectScopeExplanation": "Optionally restrict this token to a specific project. Leave empty for access to all projects.",
+        "includeSubProjects": "Include sub-projects",
+        "allProjects": "All projects",
+        "withSubProjects": "+ sub-projects",
         "attributes": {
           "title": "Title",
           "titlePlaceholder": "Enter a title you will recognize later",
           "expiresAt": "Expires at",
-          "permissions": "Permissions"
+          "permissions": "Permissions",
+          "projectScope": "Project scope"
         }
       },
       "sessions": {
diff --git a/frontend/src/modelTypes/IApiToken.ts b/frontend/src/modelTypes/IApiToken.ts
index 189549c4d..1ee14d2e4 100644
--- a/frontend/src/modelTypes/IApiToken.ts
+++ b/frontend/src/modelTypes/IApiToken.ts
@@ -10,5 +10,7 @@ export interface IApiToken extends IAbstract {
 	token: string
 	permissions: IApiPermission
 	expiresAt: Date
+	projectId: number
+	includeSubProjects: boolean
 	created: Date
 }
diff --git a/frontend/src/models/apiTokenModel.ts b/frontend/src/models/apiTokenModel.ts
index a23227004..c17dac368 100644
--- a/frontend/src/models/apiTokenModel.ts
+++ b/frontend/src/models/apiTokenModel.ts
@@ -7,6 +7,8 @@ export default class ApiTokenModel extends AbstractModel<IApiToken> {
 	token = ''
 	permissions = null
 	expiresAt: Date = null
+	projectId = 0
+	includeSubProjects = false
 	created: Date = null
 	
 	constructor(data: Partial<IApiToken> = {}) {
diff --git a/frontend/src/views/user/settings/ApiTokens.vue b/frontend/src/views/user/settings/ApiTokens.vue
index 6c7f81624..d61543398 100644
--- a/frontend/src/views/user/settings/ApiTokens.vue
+++ b/frontend/src/views/user/settings/ApiTokens.vue
@@ -16,6 +16,9 @@ import {useI18n} from 'vue-i18n'
 import Message from '@/components/misc/Message.vue'
 import FormField from '@/components/input/FormField.vue'
 import type {IApiToken} from '@/modelTypes/IApiToken'
+import type {IProject} from '@/modelTypes/IProject'
+import ProjectSearch from '@/components/tasks/partials/ProjectSearch.vue'
+import {useProjectStore} from '@/stores/projects'
 
 const service = new ApiTokenService()
 const tokens = ref<IApiToken[]>([])
@@ -32,9 +35,14 @@ const newTokenPermissionValid = ref(true)
 const apiTokenTitle = ref()
 const tokenCreatedSuccessMessage = ref('')
 
+const selectedProject = ref<IProject | null>(null)
+const includeSubProjects = ref(false)
+
 const showDeleteModal = ref<boolean>(false)
 const tokenToDelete = ref<IApiToken>()
 
+const projectStore = useProjectStore()
+
 const {t} = useI18n()
 
 const route = useRoute()
@@ -158,11 +166,16 @@ async function createToken() {
 		newToken.value.expiresAt = new Date(newTokenExpiryCustom.value)
 	}
 
+	newToken.value.projectId = selectedProject.value?.id || 0
+	newToken.value.includeSubProjects = selectedProject.value ? includeSubProjects.value : false
+
 	const token = await service.create(newToken.value)
 	tokenCreatedSuccessMessage.value = t('user.settings.apiTokens.tokenCreatedSuccess', {token: token.token})
 	newToken.value = new ApiTokenModel()
 	newTokenExpiry.value = 30
 	newTokenExpiryCustom.value = new Date()
+	selectedProject.value = null
+	includeSubProjects.value = false
 	resetPermissions()
 	tokens.value.push(token)
 	showCreateForm.value = false
@@ -226,6 +239,7 @@ function toggleGroupPermissionsFromChild(group: string, checked: boolean) {
 					<tr>
 						<th>{{ $t('misc.id') }}</th>
 						<th>{{ $t('user.settings.apiTokens.attributes.title') }}</th>
+						<th>{{ $t('user.settings.apiTokens.attributes.projectScope') }}</th>
 						<th>{{ $t('user.settings.apiTokens.attributes.permissions') }}</th>
 						<th>{{ $t('user.settings.apiTokens.attributes.expiresAt') }}</th>
 						<th>{{ $t('misc.created') }}</th>
@@ -241,6 +255,23 @@ function toggleGroupPermissionsFromChild(group: string, checked: boolean) {
 					>
 						<td>{{ tk.id }}</td>
 						<td>{{ tk.title }}</td>
+						<td>
+							<template v-if="tk.projectId">
+								{{ projectStore.projects[tk.projectId]?.title || `#${tk.projectId}` }}
+								<span
+									v-if="tk.includeSubProjects"
+									class="has-text-grey"
+								>
+									({{ $t('user.settings.apiTokens.withSubProjects') }})
+								</span>
+							</template>
+							<span
+								v-else
+								class="has-text-grey"
+							>
+								{{ $t('user.settings.apiTokens.allProjects') }}
+							</span>
+						</td>
 						<td class="is-capitalized">
 							<template
 								v-for="(v, p) in tk.permissions"
@@ -330,6 +361,24 @@ function toggleGroupPermissionsFromChild(group: string, checked: boolean) {
 				</div>
 			</div>
 
+			<!-- Project Scope -->
+			<div class="field">
+				<label class="label">{{ $t('user.settings.apiTokens.attributes.projectScope') }}</label>
+				<p class="mbe-2">
+					{{ $t('user.settings.apiTokens.projectScopeExplanation') }}
+				</p>
+				<ProjectSearch
+					v-model="selectedProject"
+				/>
+				<FancyCheckbox
+					v-if="selectedProject && selectedProject.id"
+					v-model="includeSubProjects"
+					class="mbs-2"
+				>
+					{{ $t('user.settings.apiTokens.includeSubProjects') }}
+				</FancyCheckbox>
+			</div>
+
 			<!-- Permissions -->
 			<div class="field">
 				<label class="label">{{ $t('user.settings.apiTokens.attributes.permissions') }}</label>
diff --git a/pkg/db/fixtures/api_tokens.yml b/pkg/db/fixtures/api_tokens.yml
index fae073256..353dd6d5a 100644
--- a/pkg/db/fixtures/api_tokens.yml
+++ b/pkg/db/fixtures/api_tokens.yml
@@ -28,3 +28,27 @@
   owner_id: 2
   created: 2023-09-01 07:00:00
   # token in plaintext is tk_5e29ae2ae079781ff73b0a3e0fe4d75a0b8dcb7c
+# Project-scoped token for user 1, scoped to project 1 (no sub-projects)
+- id: 4
+  title: 'project scoped token'
+  token_salt: abcTokenSlt
+  token_hash: 4f87c7025e7b4847c6eeeb89b4c258e3a0c4e7e2b8f3d1a6c5b9e2d4f7a8b3c1e6d5f4a3b2c1d0e9f8a7b6c5d4e3f2a1
+  token_last_eight: aabbccdd
+  permissions: '{"tasks":["read_all","update"],"projects":["read_all","read_one"]}'
+  expires_at: 2099-01-01 00:00:00
+  owner_id: 1
+  project_id: 1
+  include_sub_projects: 0
+  created: 2023-09-01 07:00:00
+# Project-scoped token for user 1, scoped to project 1 (with sub-projects)
+- id: 5
+  title: 'project scoped token with sub-projects'
+  token_salt: defTokenSlt
+  token_hash: 5f87c7025e7b4847c6eeeb89b4c258e3a0c4e7e2b8f3d1a6c5b9e2d4f7a8b3c1e6d5f4a3b2c1d0e9f8a7b6c5d4e3f2a1
+  token_last_eight: ddeeffaa
+  permissions: '{"tasks":["read_all","update"],"projects":["read_all","read_one"]}'
+  expires_at: 2099-01-01 00:00:00
+  owner_id: 1
+  project_id: 1
+  include_sub_projects: 1
+  created: 2023-09-01 07:00:00
diff --git a/pkg/migration/20260322120000.go b/pkg/migration/20260322120000.go
new file mode 100644
index 000000000..c3e682aed
--- /dev/null
+++ b/pkg/migration/20260322120000.go
@@ -0,0 +1,44 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package migration
+
+import (
+	"src.techknowlogick.com/xormigrate"
+	"xorm.io/xorm"
+)
+
+type apiTokens20260322120000 struct {
+	ProjectID          int64 `xorm:"bigint null index" json:"project_id"`
+	IncludeSubProjects bool  `xorm:"not null default false" json:"include_sub_projects"`
+}
+
+func (apiTokens20260322120000) TableName() string {
+	return "api_tokens"
+}
+
+func init() {
+	migrations = append(migrations, &xormigrate.Migration{
+		ID:          "20260322120000",
+		Description: "Add project scope fields to api tokens",
+		Migrate: func(tx *xorm.Engine) error {
+			return tx.Sync2(apiTokens20260322120000{})
+		},
+		Rollback: func(tx *xorm.Engine) error {
+			return nil
+		},
+	})
+}
diff --git a/pkg/models/api_tokens.go b/pkg/models/api_tokens.go
index 00ae5b747..1c43c1928 100644
--- a/pkg/models/api_tokens.go
+++ b/pkg/models/api_tokens.go
@@ -48,6 +48,10 @@ type APIToken struct {
 	APIPermissions APIPermissions `xorm:"json not null permissions" json:"permissions" valid:"required"`
 	// The date when this key expires.
 	ExpiresAt time.Time `xorm:"not null" json:"expires_at" valid:"required"`
+	// When set, restricts this token to only access resources belonging to this project.
+	ProjectID int64 `xorm:"bigint null index" json:"project_id"`
+	// When true and ProjectID is set, the token also covers all descendant sub-projects.
+	IncludeSubProjects bool `xorm:"not null default false" json:"include_sub_projects"`
 
 	// A timestamp when this api key was created. You cannot change this value.
 	Created time.Time `xorm:"created not null" json:"created"`
@@ -105,6 +109,22 @@ func (t *APIToken) Create(s *xorm.Session, a web.Auth) (err error) {
 		return err
 	}
 
+	if t.ProjectID != 0 {
+		// Verify the project exists and the token owner has at least read access
+		p := &Project{ID: t.ProjectID}
+		canRead, _, err := p.CanRead(s, a)
+		if err != nil {
+			return err
+		}
+		if !canRead {
+			return ErrProjectDoesNotExist{ID: t.ProjectID}
+		}
+	}
+
+	if t.IncludeSubProjects && t.ProjectID == 0 {
+		t.IncludeSubProjects = false
+	}
+
 	_, err = s.Insert(t)
 	return err
 }
diff --git a/pkg/models/api_tokens_project_scope.go b/pkg/models/api_tokens_project_scope.go
new file mode 100644
index 000000000..4801c764e
--- /dev/null
+++ b/pkg/models/api_tokens_project_scope.go
@@ -0,0 +1,70 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package models
+
+import (
+	"xorm.io/xorm"
+)
+
+// GetProjectIDsForToken returns the list of project IDs a token is scoped to.
+// Returns nil if the token has no project scope (user-wide token).
+func GetProjectIDsForToken(s *xorm.Session, token *APIToken) ([]int64, error) {
+	if token.ProjectID == 0 {
+		return nil, nil
+	}
+
+	if !token.IncludeSubProjects {
+		return []int64{token.ProjectID}, nil
+	}
+
+	// Use recursive CTE to get all descendant project IDs
+	var descendantIDs []int64
+	err := s.SQL(
+		`WITH RECURSIVE descendant_ids (id) AS (
+    SELECT id
+    FROM projects
+    WHERE id = ?
+    UNION ALL
+    SELECT p.id
+    FROM projects p
+    INNER JOIN descendant_ids di ON p.parent_project_id = di.id
+)
+SELECT id FROM descendant_ids`,
+		token.ProjectID,
+	).Find(&descendantIDs)
+	if err != nil {
+		return nil, err
+	}
+
+	return descendantIDs, nil
+}
+
+// ProjectScopeContains checks if the given project ID is within the token's project scope.
+// If scopedProjectIDs is nil, the token is unscoped and all projects are allowed.
+func ProjectScopeContains(scopedProjectIDs []int64, projectID int64) bool {
+	if scopedProjectIDs == nil {
+		return true
+	}
+
+	for _, id := range scopedProjectIDs {
+		if id == projectID {
+			return true
+		}
+	}
+
+	return false
+}
diff --git a/pkg/models/api_tokens_project_scope_test.go b/pkg/models/api_tokens_project_scope_test.go
new file mode 100644
index 000000000..650e39b74
--- /dev/null
+++ b/pkg/models/api_tokens_project_scope_test.go
@@ -0,0 +1,134 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package models
+
+import (
+	"testing"
+
+	"code.vikunja.io/api/pkg/db"
+	"code.vikunja.io/api/pkg/user"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestProjectScopeEnforcement(t *testing.T) {
+	t.Run("scoped auth can read project in scope", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{1}}
+
+		p := &Project{ID: 1}
+		can, _, err := p.CanRead(s, scoped)
+		require.NoError(t, err)
+		assert.True(t, can)
+	})
+	t.Run("scoped auth cannot read project outside scope", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+		// User 1 owns project 1, but token is scoped to project 6 (which user 1 also has access to)
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{6}}
+
+		p := &Project{ID: 1}
+		can, _, err := p.CanRead(s, scoped)
+		require.NoError(t, err)
+		assert.False(t, can)
+	})
+	t.Run("scoped auth cannot write to project outside scope", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{6}}
+
+		p := &Project{ID: 1}
+		can, err := p.CanWrite(s, scoped)
+		require.NoError(t, err)
+		assert.False(t, can)
+	})
+	t.Run("scoped auth can write to project in scope", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{1}}
+
+		p := &Project{ID: 1}
+		can, err := p.CanWrite(s, scoped)
+		require.NoError(t, err)
+		assert.True(t, can)
+	})
+	t.Run("scoped auth cannot delete project outside scope", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{6}}
+
+		p := &Project{ID: 1}
+		can, err := p.IsAdmin(s, scoped)
+		require.NoError(t, err)
+		assert.False(t, can)
+	})
+	t.Run("unscoped auth can read any project it has access to", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+
+		p := &Project{ID: 1}
+		can, _, err := p.CanRead(s, u)
+		require.NoError(t, err)
+		assert.True(t, can)
+	})
+	t.Run("scoped auth cannot create top-level projects", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{1}}
+
+		p := &Project{Title: "New Top Level"}
+		can, err := p.CanCreate(s, scoped)
+		require.NoError(t, err)
+		assert.False(t, can)
+	})
+	t.Run("scoped auth can create sub-project under scoped project", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{1}}
+
+		p := &Project{Title: "Sub Project", ParentProjectID: 1}
+		can, err := p.CanCreate(s, scoped)
+		require.NoError(t, err)
+		assert.True(t, can)
+	})
+}
diff --git a/pkg/models/api_tokens_test.go b/pkg/models/api_tokens_test.go
index e0ebca8d6..aaf8e42c1 100644
--- a/pkg/models/api_tokens_test.go
+++ b/pkg/models/api_tokens_test.go
@@ -39,11 +39,13 @@ func TestAPIToken_ReadAll(t *testing.T) {
 	require.NoError(t, err)
 	tokens, is := result.([]*APIToken)
 	assert.Truef(t, is, "tokens are not of type []*APIToken")
-	assert.Len(t, tokens, 2)
+	assert.Len(t, tokens, 4)
 	assert.Len(t, tokens, count)
-	assert.Equal(t, int64(2), total)
+	assert.Equal(t, int64(4), total)
 	assert.Equal(t, int64(1), tokens[0].ID)
 	assert.Equal(t, int64(2), tokens[1].ID)
+	assert.Equal(t, int64(4), tokens[2].ID)
+	assert.Equal(t, int64(5), tokens[3].ID)
 }
 
 func TestAPIToken_CanDelete(t *testing.T) {
@@ -93,6 +95,143 @@ func TestAPIToken_Create(t *testing.T) {
 		err := token.Create(s, u)
 		require.NoError(t, err)
 	})
+	t.Run("with project scope", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		token := &APIToken{
+			ProjectID: 1,
+		}
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		err := token.Create(s, u)
+		require.NoError(t, err)
+		assert.Equal(t, int64(1), token.ProjectID)
+		assert.False(t, token.IncludeSubProjects)
+	})
+	t.Run("with project scope and sub-projects", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		token := &APIToken{
+			ProjectID:          1,
+			IncludeSubProjects: true,
+		}
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		err := token.Create(s, u)
+		require.NoError(t, err)
+		assert.Equal(t, int64(1), token.ProjectID)
+		assert.True(t, token.IncludeSubProjects)
+	})
+	t.Run("with nonexistent project", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		token := &APIToken{
+			ProjectID: 999999,
+		}
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		err := token.Create(s, u)
+		require.Error(t, err)
+		assert.True(t, IsErrProjectDoesNotExist(err))
+	})
+	t.Run("with project user has no access to", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		token := &APIToken{
+			ProjectID: 2, // owned by user 3
+		}
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		err := token.Create(s, u)
+		require.Error(t, err)
+		assert.True(t, IsErrProjectDoesNotExist(err))
+	})
+	t.Run("include sub-projects without project ID is ignored", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		token := &APIToken{
+			IncludeSubProjects: true,
+		}
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		err := token.Create(s, u)
+		require.NoError(t, err)
+		assert.False(t, token.IncludeSubProjects)
+	})
+}
+
+func TestGetProjectIDsForToken(t *testing.T) {
+	t.Run("no project scope", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		ids, err := GetProjectIDsForToken(s, &APIToken{ProjectID: 0})
+		require.NoError(t, err)
+		assert.Nil(t, ids)
+	})
+	t.Run("single project", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		ids, err := GetProjectIDsForToken(s, &APIToken{ProjectID: 1, IncludeSubProjects: false})
+		require.NoError(t, err)
+		assert.Equal(t, []int64{1}, ids)
+	})
+	t.Run("with sub-projects", func(t *testing.T) {
+		s := db.NewSession()
+		defer s.Close()
+		db.LoadAndAssertFixtures(t)
+
+		// Project 22 has child project 21
+		ids, err := GetProjectIDsForToken(s, &APIToken{ProjectID: 22, IncludeSubProjects: true})
+		require.NoError(t, err)
+		assert.Contains(t, ids, int64(22))
+		assert.Contains(t, ids, int64(21))
+	})
+}
+
+func TestProjectScopeContains(t *testing.T) {
+	t.Run("nil scope allows all", func(t *testing.T) {
+		assert.True(t, ProjectScopeContains(nil, 1))
+		assert.True(t, ProjectScopeContains(nil, 999))
+	})
+	t.Run("scope contains project", func(t *testing.T) {
+		assert.True(t, ProjectScopeContains([]int64{1, 2, 3}, 2))
+	})
+	t.Run("scope does not contain project", func(t *testing.T) {
+		assert.False(t, ProjectScopeContains([]int64{1, 2, 3}, 5))
+	})
+}
+
+func TestProjectScopedAuth(t *testing.T) {
+	t.Run("GetID delegates to inner auth", func(t *testing.T) {
+		u := &user.User{ID: 42}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{1}}
+		assert.Equal(t, int64(42), scoped.GetID())
+	})
+	t.Run("GetProjectScope returns scope", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{1, 2}}
+		scope := GetProjectScope(scoped)
+		assert.Equal(t, []int64{1, 2}, scope)
+	})
+	t.Run("GetProjectScope returns nil for regular auth", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		scope := GetProjectScope(u)
+		assert.Nil(t, scope)
+	})
+	t.Run("UnwrapAuth returns inner auth", func(t *testing.T) {
+		u := &user.User{ID: 1}
+		scoped := &ProjectScopedAuth{Auth: u, ProjectIDs: []int64{1}}
+		assert.Equal(t, u, scoped.UnwrapAuth())
+	})
 }
 
 func TestAPIToken_GetTokenFromTokenString(t *testing.T) {
diff --git a/pkg/models/project.go b/pkg/models/project.go
index 64f46148c..8851da86e 100644
--- a/pkg/models/project.go
+++ b/pkg/models/project.go
@@ -262,6 +262,19 @@ func getAllRawProjects(s *xorm.Session, a web.Auth, search string, page int, per
 		prs = append(prs, savedFiltersProject...)
 	}
 
+	// Filter by project scope if using a project-scoped API token
+	if scope := GetProjectScope(a); scope != nil {
+		filtered := make([]*Project, 0, len(prs))
+		for _, pr := range prs {
+			if ProjectScopeContains(scope, pr.ID) {
+				filtered = append(filtered, pr)
+			}
+		}
+		prs = filtered
+		resultCount = len(prs)
+		totalItems = int64(len(prs))
+	}
+
 	return prs, resultCount, totalItems, err
 }
 
diff --git a/pkg/models/project_permissions.go b/pkg/models/project_permissions.go
index ea22983af..88e26cfb1 100644
--- a/pkg/models/project_permissions.go
+++ b/pkg/models/project_permissions.go
@@ -34,6 +34,11 @@ func (p *Project) CanWrite(s *xorm.Session, a web.Auth) (bool, error) {
 		return false, nil
 	}
 
+	// Check project scope from API token
+	if scope := GetProjectScope(a); scope != nil && !ProjectScopeContains(scope, p.ID) {
+		return false, nil
+	}
+
 	// Get the project and check the permission
 	originalProject, err := GetProjectSimpleByID(s, p.ID)
 	if err != nil {
@@ -92,6 +97,11 @@ func (p *Project) CanRead(s *xorm.Session, a web.Auth) (bool, int, error) {
 		return sf.CanRead(s, a)
 	}
 
+	// Check project scope from API token
+	if scope := GetProjectScope(a); scope != nil && !ProjectScopeContains(scope, p.ID) {
+		return false, 0, nil
+	}
+
 	// Check if the user is either owner or can read
 	var err error
 	originalProject, err := GetProjectSimpleByID(s, p.ID)
@@ -165,6 +175,10 @@ func (p *Project) CanDelete(s *xorm.Session, a web.Auth) (bool, error) {
 // CanCreate checks if the user can create a project
 func (p *Project) CanCreate(s *xorm.Session, a web.Auth) (bool, error) {
 	if p.ParentProjectID != 0 {
+		// Check project scope: parent must be in scope
+		if scope := GetProjectScope(a); scope != nil && !ProjectScopeContains(scope, p.ParentProjectID) {
+			return false, nil
+		}
 		parent := &Project{ID: p.ParentProjectID}
 		return parent.CanWrite(s, a)
 	}
@@ -173,6 +187,10 @@ func (p *Project) CanCreate(s *xorm.Session, a web.Auth) (bool, error) {
 	if is {
 		return false, nil
 	}
+	// Project-scoped tokens cannot create top-level projects
+	if scope := GetProjectScope(a); scope != nil {
+		return false, nil
+	}
 	return true, nil
 }
 
@@ -183,6 +201,11 @@ func (p *Project) IsAdmin(s *xorm.Session, a web.Auth) (bool, error) {
 		return false, nil
 	}
 
+	// Check project scope from API token
+	if scope := GetProjectScope(a); scope != nil && !ProjectScopeContains(scope, p.ID) {
+		return false, nil
+	}
+
 	originalProject, err := GetProjectSimpleByID(s, p.ID)
 	if err != nil {
 		return false, err
diff --git a/pkg/models/project_scoped_auth.go b/pkg/models/project_scoped_auth.go
new file mode 100644
index 000000000..6e59ab781
--- /dev/null
+++ b/pkg/models/project_scoped_auth.go
@@ -0,0 +1,48 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package models
+
+import (
+	"code.vikunja.io/api/pkg/web"
+)
+
+// ProjectScopedAuth wraps a web.Auth and adds project scope restrictions
+// from a project-scoped API token. Models can type-assert to this type
+// to check and enforce project scope.
+type ProjectScopedAuth struct {
+	Auth       web.Auth
+	ProjectIDs []int64
+}
+
+// GetID implements the web.Auth interface by delegating to the wrapped auth.
+func (p *ProjectScopedAuth) GetID() int64 {
+	return p.Auth.GetID()
+}
+
+// UnwrapAuth implements web.AuthUnwrapper to allow type assertions on the inner auth.
+func (p *ProjectScopedAuth) UnwrapAuth() web.Auth {
+	return p.Auth
+}
+
+// GetProjectScope extracts project scope IDs from a web.Auth, if present.
+// Returns nil if the auth is not project-scoped (meaning all projects are accessible).
+func GetProjectScope(a web.Auth) []int64 {
+	if scoped, ok := a.(*ProjectScopedAuth); ok {
+		return scoped.ProjectIDs
+	}
+	return nil
+}
diff --git a/pkg/models/task_collection.go b/pkg/models/task_collection.go
index 06a1799e1..c5e4ddf64 100644
--- a/pkg/models/task_collection.go
+++ b/pkg/models/task_collection.go
@@ -185,7 +185,22 @@ func getRelevantProjectsFromCollection(s *xorm.Session, a web.Auth, tf *TaskColl
 				page: -1,
 			},
 		)
-		return projects, err
+		if err != nil {
+			return nil, err
+		}
+
+		// Filter by project scope if using a project-scoped API token
+		if scope := GetProjectScope(a); scope != nil {
+			filtered := make([]*Project, 0, len(projects))
+			for _, p := range projects {
+				if ProjectScopeContains(scope, p.ID) {
+					filtered = append(filtered, p)
+				}
+			}
+			projects = filtered
+		}
+
+		return projects, nil
 	}
 
 	// Check the project exists and the user has access on it
diff --git a/pkg/modules/auth/auth.go b/pkg/modules/auth/auth.go
index 476416695..6ed72acac 100644
--- a/pkg/modules/auth/auth.go
+++ b/pkg/modules/auth/auth.go
@@ -170,6 +170,15 @@ func GetAuthFromClaims(c *echo.Context) (a web.Auth, err error) {
 		if err != nil {
 			return nil, err
 		}
+
+		// Wrap with project scope if the token is project-scoped
+		if projectIDs, ok := c.Get("api_token_project_ids").([]int64); ok && len(projectIDs) > 0 {
+			return &models.ProjectScopedAuth{
+				Auth:       u,
+				ProjectIDs: projectIDs,
+			}, nil
+		}
+
 		return u, nil
 	}
 
diff --git a/pkg/routes/api_tokens.go b/pkg/routes/api_tokens.go
index 015b3542b..80af559dc 100644
--- a/pkg/routes/api_tokens.go
+++ b/pkg/routes/api_tokens.go
@@ -99,5 +99,13 @@ func checkAPITokenAndPutItInContext(tokenHeaderValue string, c *echo.Context) er
 	c.Set("api_token", token)
 	c.Set("api_user", u)
 
+	if token.ProjectID != 0 {
+		projectIDs, err := models.GetProjectIDsForToken(s, token)
+		if err != nil {
+			return echo.NewHTTPError(http.StatusInternalServerError, "Internal Server Error").Wrap(err)
+		}
+		c.Set("api_token_project_ids", projectIDs)
+	}
+
 	return nil
 }
diff --git a/pkg/user/user.go b/pkg/user/user.go
index 53a9b8121..003a276b7 100644
--- a/pkg/user/user.go
+++ b/pkg/user/user.go
@@ -203,6 +203,11 @@ func (u *User) GetFailedPasswordAttemptsKey() string {
 // GetFromAuth returns a user object from a web.Auth object and returns an error if the underlying type
 // is not a user object
 func GetFromAuth(a web.Auth) (*User, error) {
+	// Unwrap wrapper types (e.g. ProjectScopedAuth) to get the underlying auth
+	if unwrapper, ok := a.(web.AuthUnwrapper); ok {
+		a = unwrapper.UnwrapAuth()
+	}
+
 	u, is := a.(*User)
 	if !is {
 		typ := reflect.TypeOf(a)
diff --git a/pkg/web/web.go b/pkg/web/web.go
index 98ef4f06c..dd2856d19 100644
--- a/pkg/web/web.go
+++ b/pkg/web/web.go
@@ -61,6 +61,12 @@ type Auth interface {
 	GetID() int64
 }
 
+// AuthUnwrapper can be implemented by auth wrappers (e.g. project-scoped auth)
+// to allow unwrapping to the underlying auth object.
+type AuthUnwrapper interface {
+	UnwrapAuth() Auth
+}
+
 // Authprovider holds the implementation of an auth provider used by the application
 type Authprovider interface {
 	GetAuthObject(echo.Context) (Auth, error)