diff --git a/src/app/shared/services/contributors.service.spec.ts b/src/app/shared/services/contributors.service.spec.ts
new file mode 100644
index 000000000..b9666d4be
--- /dev/null
+++ b/src/app/shared/services/contributors.service.spec.ts
@@ -0,0 +1,345 @@
+import { MockProvider } from 'ng-mocks';
+
+import { firstValueFrom } from 'rxjs';
+
+import { HttpTestingController } from '@angular/common/http/testing';
+import { TestBed } from '@angular/core/testing';
+
+import { ENVIRONMENT_DO_NO_USE } from '@core/constants/environment.token';
+import { ContributorPermission } from '@osf/shared/enums/contributors/contributor-permission.enum';
+import { ResourceType } from '@osf/shared/enums/resource-type.enum';
+import { ContributorModel } from '@osf/shared/models/contributors/contributor.model';
+import { ContributorAddModel } from '@osf/shared/models/contributors/contributor-add.model';
+
+import { ContributorsService } from './contributors.service';
+
+import {
+  getContributorsListData,
+  getContributorsSearchData,
+  getContributorsSearchDataSecondUser,
+  getContributorsSearchDataWithPagination,
+} from '@testing/data/contributors/contributors.data';
+import { provideOSFCore, provideOSFHttp } from '@testing/osf.testing.provider';
+
+const SHARE_TROVE_URL = 'https://share.osf.io/trove';
+const API_URL = 'http://localhost:8000/v2';
+const WEB_URL = 'http://localhost:4200';
+
+describe('ContributorsService', () => {
+  let service: ContributorsService;
+
+  beforeEach(() => {
+    TestBed.configureTestingModule({
+      providers: [
+        provideOSFCore(),
+        provideOSFHttp(),
+        MockProvider(ENVIRONMENT_DO_NO_USE, {
+          production: false,
+          apiDomainUrl: 'http://localhost:8000',
+          shareTroveUrl: SHARE_TROVE_URL,
+          webUrl: WEB_URL,
+        }),
+        ContributorsService,
+      ],
+    });
+
+    service = TestBed.inject(ContributorsService);
+  });
+
+  it('getUsersByLink should set isBibliographic: true for users returned from search', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.getUsersByLink(`${SHARE_TROVE_URL}/index-card-search`));
+
+    const req = httpMock.expectOne(`${SHARE_TROVE_URL}/index-card-search`);
+    expect(req.request.method).toBe('GET');
+    req.flush(getContributorsSearchData());
+
+    const result = await resultPromise;
+    expect(result.users[0].isBibliographic).toBe(true);
+    expect(result.users[0].permission).toBe(ContributorPermission.Write);
+    expect(result.users[0].fullName).toBe('Test User');
+    expect(result.users[0].id).toBe('abc12');
+    expect(result.totalCount).toBe(1);
+    expect(result.next).toBeNull();
+    expect(result.previous).toBeNull();
+
+    httpMock.verify();
+  });
+
+  it('getUsersByLink should return next and previous pagination links when present', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.getUsersByLink(`${SHARE_TROVE_URL}/index-card-search`));
+
+    const req = httpMock.expectOne(`${SHARE_TROVE_URL}/index-card-search`);
+    req.flush(getContributorsSearchDataWithPagination());
+
+    const result = await resultPromise;
+    expect(result.next).toBe('https://share.osf.io/trove/index-card-search?page=2');
+    expect(result.previous).toBe('https://share.osf.io/trove/index-card-search?page=1');
+
+    httpMock.verify();
+  });
+
+  it('searchUsersByName should search by name with correct query params', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.searchUsersByName('alice'));
+
+    const req = httpMock.expectOne((request) => request.url === `${SHARE_TROVE_URL}/index-card-search`);
+    expect(req.request.method).toBe('GET');
+    expect(req.request.params.get('cardSearchFilter[resourceType]')).toBe('Person');
+    expect(req.request.params.get('cardSearchText[name]')).toBe('alice*');
+    req.flush(getContributorsSearchData());
+
+    const result = await resultPromise;
+    expect(result.users[0].isBibliographic).toBe(true);
+
+    httpMock.verify();
+  });
+
+  it('searchUsersById should search by id with correct query params', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.searchUsersById('abc12'));
+
+    const req = httpMock.expectOne((request) => request.url === `${SHARE_TROVE_URL}/index-card-search`);
+    expect(req.request.method).toBe('GET');
+    expect(req.request.params.get('cardSearchFilter[sameAs]')).toBe(`${WEB_URL}/abc12`);
+    req.flush(getContributorsSearchData());
+
+    const result = await resultPromise;
+    expect(result.users[0].isBibliographic).toBe(true);
+
+    httpMock.verify();
+  });
+
+  it('searchUsers should call only searchUsersByName when value length is not 5', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.searchUsers('ali'));
+
+    const reqs = httpMock.match((request) => request.url === `${SHARE_TROVE_URL}/index-card-search`);
+    expect(reqs.length).toBe(1);
+    reqs[0].flush(getContributorsSearchData());
+
+    const result = await resultPromise;
+    expect(result.users.length).toBe(1);
+
+    httpMock.verify();
+  });
+
+  it('searchUsers should forkJoin name and id searches when value length is 5 and deduplicate results', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.searchUsers('alice'));
+
+    const reqs = httpMock.match((request) => request.url === `${SHARE_TROVE_URL}/index-card-search`);
+    expect(reqs.length).toBe(2);
+    reqs[0].flush(getContributorsSearchData());
+    reqs[1].flush(getContributorsSearchData());
+
+    const result = await resultPromise;
+    expect(result.users.length).toBe(1);
+
+    httpMock.verify();
+  });
+
+  it('searchUsers should merge unique users from name and id searches', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.searchUsers('alice'));
+
+    const reqs = httpMock.match((request) => request.url === `${SHARE_TROVE_URL}/index-card-search`);
+    expect(reqs.length).toBe(2);
+    reqs[0].flush(getContributorsSearchData());
+    reqs[1].flush(getContributorsSearchDataSecondUser());
+
+    const result = await resultPromise;
+    expect(result.users.length).toBe(2);
+    expect(result.users[0].id).toBe('abc12');
+    expect(result.users[1].id).toBe('xyz99');
+
+    httpMock.verify();
+  });
+
+  it('getAllContributors should GET contributors with pagination params', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.getAllContributors(ResourceType.Project, 'node-id', 1, 10));
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/?page=1&page%5Bsize%5D=10`);
+    expect(req.request.method).toBe('GET');
+    req.flush(getContributorsListData());
+
+    const result = await resultPromise;
+    expect(result.totalCount).toBe(1);
+    expect(result.data[0].isBibliographic).toBe(true);
+
+    httpMock.verify();
+  });
+
+  it('getBibliographicContributors should GET bibliographic_contributors endpoint', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.getBibliographicContributors(ResourceType.Project, 'node-id', 1, 10));
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/bibliographic_contributors/?page=1&page%5Bsize%5D=10`);
+    expect(req.request.method).toBe('GET');
+    req.flush(getContributorsListData());
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('bulkAddContributors should return empty array when contributors list is empty', async () => {
+    const result = await firstValueFrom(service.bulkAddContributors(ResourceType.Project, 'node-id', []));
+    expect(result).toEqual([]);
+  });
+
+  it('bulkAddContributors should POST registered contributor with correct payload', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+    const contributor: ContributorAddModel = {
+      id: 'user-id',
+      fullName: 'John Doe',
+      isBibliographic: true,
+      permission: ContributorPermission.Write,
+    };
+
+    const resultPromise = firstValueFrom(service.bulkAddContributors(ResourceType.Project, 'node-id', [contributor]));
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/`);
+    expect(req.request.method).toBe('POST');
+    expect(req.request.body.data[0].type).toBe('contributors');
+    expect(req.request.body.data[0].attributes.bibliographic).toBe(true);
+    req.flush(getContributorsListData());
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('bulkAddContributors should POST unregistered contributor when id is missing', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+    const contributor: ContributorAddModel = {
+      fullName: 'Unregistered User',
+      email: 'new@example.com',
+      isBibliographic: false,
+      permission: ContributorPermission.Read,
+    };
+
+    const resultPromise = firstValueFrom(service.bulkAddContributors(ResourceType.Project, 'node-id', [contributor]));
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/`);
+    expect(req.request.method).toBe('POST');
+    expect(req.request.body.data[0].attributes.full_name).toBe('Unregistered User');
+    req.flush(getContributorsListData());
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('bulkAddContributors should POST with childNodeIds when provided', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+    const contributor: ContributorAddModel = {
+      id: 'user-id',
+      fullName: 'John Doe',
+      isBibliographic: true,
+      permission: ContributorPermission.Write,
+    };
+
+    const resultPromise = firstValueFrom(
+      service.bulkAddContributors(ResourceType.Project, 'node-id', [contributor], ['child-1'])
+    );
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/`);
+    expect(req.request.body.data[0].attributes.child_nodes).toEqual(['child-1']);
+    req.flush(getContributorsListData());
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('bulkUpdateContributors should return empty array when contributors list is empty', async () => {
+    const result = await firstValueFrom(service.bulkUpdateContributors(ResourceType.Project, 'node-id', []));
+    expect(result).toEqual([]);
+  });
+
+  it('bulkUpdateContributors should PATCH contributors with correct payload', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+    const contributor: ContributorModel = {
+      id: 'node-id-user-id',
+      userId: 'user-id',
+      type: 'contributors',
+      fullName: 'John Doe',
+      givenName: 'John',
+      familyName: 'Doe',
+      isUnregisteredContributor: false,
+      permission: ContributorPermission.Write,
+      isBibliographic: true,
+      isCurator: false,
+      index: 0,
+      education: [],
+      employment: [],
+      deactivated: false,
+    };
+
+    const resultPromise = firstValueFrom(
+      service.bulkUpdateContributors(ResourceType.Project, 'node-id', [contributor])
+    );
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/`);
+    expect(req.request.method).toBe('PATCH');
+    expect(req.request.body.data[0].id).toBe('node-id-user-id');
+    expect(req.request.body.data[0].attributes.bibliographic).toBe(true);
+    req.flush(getContributorsListData());
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('addContributorsFromProject should PATCH with copy_contributors_from_parent_project param', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.addContributorsFromProject(ResourceType.Project, 'node-id'));
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/?copy_contributors_from_parent_project=true`);
+    expect(req.request.method).toBe('PATCH');
+    req.flush(null);
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('deleteContributor should DELETE contributor by userId', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.deleteContributor(ResourceType.Project, 'node-id', 'user-id'));
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/user-id/`);
+    expect(req.request.method).toBe('DELETE');
+    req.flush(null);
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('deleteContributor should DELETE with include_children param when removeFromChildren is true', async () => {
+    const httpMock = TestBed.inject(HttpTestingController);
+
+    const resultPromise = firstValueFrom(service.deleteContributor(ResourceType.Project, 'node-id', 'user-id', true));
+
+    const req = httpMock.expectOne(`${API_URL}/nodes/node-id/contributors/user-id/?include_children=true`);
+    expect(req.request.method).toBe('DELETE');
+    req.flush(null);
+
+    await resultPromise;
+    httpMock.verify();
+  });
+
+  it('getBaseUrl should throw error for unsupported resource type', () => {
+    expect(() => service.getAllContributors(ResourceType.File, 'id', 1, 10).subscribe()).toThrowError(
+      'Unsupported resource type: 1'
+    );
+  });
+});
diff --git a/src/app/shared/services/contributors.service.ts b/src/app/shared/services/contributors.service.ts
index 266ba23f2..96c3754d8 100644
--- a/src/app/shared/services/contributors.service.ts
+++ b/src/app/shared/services/contributors.service.ts
@@ -172,6 +172,7 @@ export class ContributorsService {
         ({
           id: user.absoluteUrl.split('/').pop(),
           fullName: user.name,
+          isBibliographic: true,
           permission: ContributorPermission.Write,
         }) as ContributorAddModel
     );
diff --git a/src/testing/data/contributors/contributors.data.ts b/src/testing/data/contributors/contributors.data.ts
new file mode 100644
index 000000000..587b1835a
--- /dev/null
+++ b/src/testing/data/contributors/contributors.data.ts
@@ -0,0 +1,196 @@
+import { ContributorPermission } from '@osf/shared/enums/contributors/contributor-permission.enum';
+
+export function getContributorsSearchData() {
+  return {
+    data: {
+      attributes: { totalResultCount: 1 },
+      relationships: {
+        searchResultPage: {
+          data: [{ id: 'search-result-1' }],
+          links: { first: { href: '' }, next: null, prev: null },
+        },
+        relatedProperties: { data: [] },
+      },
+      links: { self: '' },
+    },
+    included: [
+      {
+        id: 'search-result-1',
+        type: 'search-result',
+        relationships: { indexCard: { data: { id: 'index-card-1', type: 'index-card' } } },
+        attributes: { matchEvidence: [], cardSearchResultCount: 1 },
+      },
+      {
+        id: 'index-card-1',
+        type: 'index-card',
+        attributes: {
+          resourceMetadata: {
+            '@id': 'https://osf.io/abc12',
+            resourceType: [{ '@id': 'Person' }],
+            name: [{ '@value': 'Test User' }],
+            title: [],
+            fileName: [],
+            description: [],
+            dateCreated: [],
+            dateModified: [],
+            dateWithdrawn: [],
+            creator: [],
+            hasVersion: [],
+            identifier: [],
+            publisher: [],
+            rights: [],
+            language: [],
+            statedConflictOfInterest: [],
+            resourceNature: [],
+            isPartOfCollection: [],
+            storageByteCount: [],
+            storageRegion: [],
+            usage: { viewCount: [], downloadCount: [] },
+            hasOsfAddon: [],
+            funder: [],
+            affiliation: [],
+            qualifiedAttribution: [],
+            isPartOf: [],
+            isContainedBy: [],
+            conformsTo: [],
+            hasPreregisteredAnalysisPlan: [],
+            hasPreregisteredStudyDesign: [],
+            hasDataResource: [],
+            hasAnalyticCodeResource: [],
+            hasMaterialsResource: [],
+            hasPapersResource: [],
+            hasSupplementalResource: [],
+          },
+          resourceIdentifier: [],
+        },
+      },
+    ],
+  };
+}
+
+export function getContributorsSearchDataWithPagination() {
+  return {
+    ...getContributorsSearchData(),
+    data: {
+      ...getContributorsSearchData().data,
+      relationships: {
+        ...getContributorsSearchData().data.relationships,
+        searchResultPage: {
+          ...getContributorsSearchData().data.relationships.searchResultPage,
+          links: {
+            first: { href: '' },
+            next: { href: 'https://share.osf.io/trove/index-card-search?page=2' },
+            prev: { href: 'https://share.osf.io/trove/index-card-search?page=1' },
+          },
+        },
+      },
+    },
+  };
+}
+
+export function getContributorsSearchDataSecondUser() {
+  return {
+    data: {
+      attributes: { totalResultCount: 1 },
+      relationships: {
+        searchResultPage: {
+          data: [{ id: 'search-result-2' }],
+          links: { first: { href: '' }, next: null, prev: null },
+        },
+        relatedProperties: { data: [] },
+      },
+      links: { self: '' },
+    },
+    included: [
+      {
+        id: 'search-result-2',
+        type: 'search-result',
+        relationships: { indexCard: { data: { id: 'index-card-2', type: 'index-card' } } },
+        attributes: { matchEvidence: [], cardSearchResultCount: 1 },
+      },
+      {
+        id: 'index-card-2',
+        type: 'index-card',
+        attributes: {
+          resourceMetadata: {
+            '@id': 'https://osf.io/xyz99',
+            resourceType: [{ '@id': 'Person' }],
+            name: [{ '@value': 'Other User' }],
+            title: [],
+            fileName: [],
+            description: [],
+            dateCreated: [],
+            dateModified: [],
+            dateWithdrawn: [],
+            creator: [],
+            hasVersion: [],
+            identifier: [],
+            publisher: [],
+            rights: [],
+            language: [],
+            statedConflictOfInterest: [],
+            resourceNature: [],
+            isPartOfCollection: [],
+            storageByteCount: [],
+            storageRegion: [],
+            usage: { viewCount: [], downloadCount: [] },
+            hasOsfAddon: [],
+            funder: [],
+            affiliation: [],
+            qualifiedAttribution: [],
+            isPartOf: [],
+            isContainedBy: [],
+            conformsTo: [],
+            hasPreregisteredAnalysisPlan: [],
+            hasPreregisteredStudyDesign: [],
+            hasDataResource: [],
+            hasAnalyticCodeResource: [],
+            hasMaterialsResource: [],
+            hasPapersResource: [],
+            hasSupplementalResource: [],
+          },
+          resourceIdentifier: [],
+        },
+      },
+    ],
+  };
+}
+
+export function getContributorsListData() {
+  return {
+    data: [
+      {
+        id: 'node-id-user-id',
+        type: 'contributors',
+        attributes: {
+          bibliographic: true,
+          index: 0,
+          is_curator: false,
+          permission: ContributorPermission.Write,
+          unregistered_contributor: null,
+        },
+        relationships: {
+          users: { links: { related: { href: '', meta: {} } }, data: { id: 'user-id', type: 'users' } },
+          node: { links: { related: { href: '', meta: {} } }, data: { id: 'node-id', type: 'nodes' } },
+        },
+        embeds: {
+          users: {
+            data: {
+              id: 'user-id',
+              type: 'users',
+              attributes: {
+                full_name: 'John Doe',
+                given_name: 'John',
+                family_name: 'Doe',
+                education: [],
+                employment: [],
+              },
+            },
+          },
+        },
+      },
+    ],
+    links: {},
+    meta: { total: 1, per_page: 10, version: '2.0' },
+  };
+}