diff --git a/backend/app/api/researchers.py b/backend/app/api/researchers.py
new file mode 100644
index 0000000..6c56d7d
--- /dev/null
+++ b/backend/app/api/researchers.py
@@ -0,0 +1,120 @@
+from fastapi import APIRouter, Depends, HTTPException
+from fastapi.responses import Response
+from sqlalchemy.orm import Session
+from app.schema.publication import PublicationSchema
+from app.db.session import get_db
+from app.repositories.researcher_repository import ResearcherRepository
+from app.repositories.publication_repository import PublicationRepository
+from app.services.sync_service import SyncService
+from app.services.sword_exporter import SWORDExporter
+from app.utils.orcid_validator import is_valid_orcid
+
+router = APIRouter(prefix="/researchers", tags=["researchers"])
+
+
+def validate_orcid_or_400(orcid_id: str):
+    if not is_valid_orcid(orcid_id):
+        raise HTTPException(
+            status_code=400,
+            detail=f"ORCID ID '{orcid_id}' no es válido según el formato y dígito de control."
+        )
+
+
+@router.post("/", response_model=dict)
+def create_researcher(orcid_id: str, db: Session = Depends(get_db)):
+    validate_orcid_or_400(orcid_id)
+
+    existing = ResearcherRepository.get_by_orcid(db, orcid_id)
+    if existing:
+        return {
+            "status": "ok",
+            "message": "Researcher ya existe.",
+            "orcid_id": existing.orcid_id,
+            "id": existing.id
+        }
+
+    # Aquí podrías opcionalmente validar que el ORCID existe en ORCID API
+    researcher = ResearcherRepository.create(db, orcid_id, name=None)
+
+    return {
+        "status": "ok",
+        "message": "Researcher creado correctamente.",
+        "orcid_id": researcher.orcid_id,
+        "id": researcher.id
+    }
+
+
+@router.get("/{orcid_id}", response_model=dict)
+def get_researcher(orcid_id: str, db: Session = Depends(get_db)):
+    validate_orcid_or_400(orcid_id)
+
+    researcher = ResearcherRepository.get_by_orcid(db, orcid_id)
+    if not researcher:
+        raise HTTPException(status_code=404, detail="Researcher not found")
+
+    return {
+        "orcid_id": researcher.orcid_id,
+        "name": researcher.name,
+        "authenticated": researcher.authenticated,
+        "access_token": researcher.access_token,
+        "id": researcher.id,
+        "last_sync_at": researcher.last_sync_at,
+    }
+
+
+@router.post("/{orcid_id}/sync", response_model=dict)
+def sync_researcher(orcid_id: str, db: Session = Depends(get_db)):
+    validate_orcid_or_400(orcid_id)
+
+    service = SyncService()
+    result = service.sync_researcher(db, orcid_id)
+    return result
+
+
+@router.get("/{orcid_id}/publications", response_model=list[PublicationSchema], tags=["researchers"])
+def get_publications(orcid_id: str, db: Session = Depends(get_db)):
+    researcher = ResearcherRepository.get_by_orcid(db, orcid_id)
+    if not researcher:
+        raise HTTPException(status_code=404, detail="Researcher not found")
+    return researcher.publications
+
+
+
+@router.get("/{orcid_id}/export/sword.xml")
+def export_sword_xml(orcid_id: str, db: Session = Depends(get_db)):
+    validate_orcid_or_400(orcid_id)
+
+    researcher = ResearcherRepository.get_by_orcid(db, orcid_id)
+    if not researcher:
+        raise HTTPException(status_code=404, detail="Researcher not found")
+
+    pubs = PublicationRepository.list_by_researcher(db, researcher.id)
+    xml_bytes = SWORDExporter.export_feed_xml(researcher, pubs)
+
+    return Response(
+        content=xml_bytes,
+        media_type="application/xml",
+        headers={
+            "Content-Disposition": f'attachment; filename="sword_{orcid_id}.xml"'
+        }
+    )
+
+
+@router.get("/{orcid_id}/export/sword.zip")
+def export_sword_zip(orcid_id: str, db: Session = Depends(get_db)):
+    validate_orcid_or_400(orcid_id)
+
+    researcher = ResearcherRepository.get_by_orcid(db, orcid_id)
+    if not researcher:
+        raise HTTPException(status_code=404, detail="Researcher not found")
+
+    pubs = PublicationRepository.list_by_researcher(db, researcher.id)
+    zip_bytes = SWORDExporter.export_zip(researcher, pubs)
+
+    return Response(
+        content=zip_bytes,
+        media_type="application/zip",
+        headers={
+            "Content-Disposition": f'attachment; filename="sword_{orcid_id}.zip"'
+        }
+    )
diff --git a/backend/app/db/models.py b/backend/app/db/models.py
index b86ea83..d91ec0c 100644
--- a/backend/app/db/models.py
+++ b/backend/app/db/models.py
@@ -1,9 +1,11 @@
-from sqlalchemy import Column, String, Boolean, Integer, DateTime, Text
+from sqlalchemy import Column, String, Boolean, Integer, DateTime, Text, ForeignKey
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.sql import func
+from sqlalchemy.orm import relationship
 from .session import Base
 import uuid
 
+
 class Researcher(Base):
     __tablename__ = "researchers"
 
@@ -11,18 +13,48 @@ class Researcher(Base):
     orcid_id = Column(String(19), unique=True, nullable=False)
     name = Column(Text)
     authenticated = Column(Boolean, default=False)
-    access_token = Column(Text)
-    last_sync_at = Column(DateTime)
+    access_token = Column(Text, nullable=True)
+    last_sync_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    publications = relationship(
+        "Publication",
+        back_populates="researcher",
+        cascade="all, delete-orphan"
+    )
+
+    sync_jobs = relationship(
+        "SyncJob",
+        back_populates="researcher",
+        cascade="all, delete-orphan"
+    )
+
 
 class Publication(Base):
     __tablename__ = "publications"
 
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
-    researcher_id = Column(UUID(as_uuid=True))
+    researcher_id = Column(UUID(as_uuid=True), ForeignKey("researchers.id"))
     put_code = Column(Integer)
     title = Column(Text)
+    journal = Column(Text)
     doi = Column(Text)
     pub_year = Column(Integer)
     type = Column(Text)
     hash_fingerprint = Column(Text)
-    last_modified = Column(DateTime)
+    last_modified = Column(DateTime(timezone=True))
+
+    researcher = relationship("Researcher", back_populates="publications")
+
+
+class SyncJob(Base):
+    __tablename__ = "sync_jobs"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    researcher_id = Column(UUID(as_uuid=True), ForeignKey("researchers.id"))
+    status = Column(String(20))
+    new_records = Column(Integer, default=0)
+    updated_records = Column(Integer, default=0)
+    started_at = Column(DateTime(timezone=True), server_default=func.now())
+    finished_at = Column(DateTime(timezone=True))
+
+    researcher = relationship("Researcher", back_populates="sync_jobs")
diff --git a/backend/app/db/session.py b/backend/app/db/session.py
index bc82b42..3f63b01 100644
--- a/backend/app/db/session.py
+++ b/backend/app/db/session.py
@@ -4,7 +4,23 @@ import os
 
 DATABASE_URL = os.getenv("DATABASE_URL")
 
-engine = create_engine(DATABASE_URL)
-SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False)
+engine = create_engine(
+    DATABASE_URL,
+    future=True,
+    echo=False
+)
+
+SessionLocal = sessionmaker(
+    autocommit=False,
+    autoflush=False,
+    bind=engine
+)
 
 Base = declarative_base()
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
diff --git a/backend/app/main.py b/backend/app/main.py
index c8dcfd2..402cbca 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -1,9 +1,32 @@
 from fastapi import FastAPI
-from app.services.orcid_client import ORCIDClient
+from app.api.researchers import router as researchers_router
+from app.db.session import Base, engine
 
-app = FastAPI()
 
-@app.get("/orcid/{orcid_id}/works")
-def test_works(orcid_id: str):
-    client = ORCIDClient()
-    return client.fetch_works(orcid_id)
+app = FastAPI(
+    title="ORCID SWORD Backend",
+    description="Backend para sincronización ORCID y exportación SWORD",
+    version="1.0.0"
+)
+
+
+# ---------------------------------------------------------
+# Crear tablas al iniciar la aplicación
+# ---------------------------------------------------------
+@app.on_event("startup")
+def startup_event():
+    Base.metadata.create_all(bind=engine)
+
+
+# ---------------------------------------------------------
+# Healthcheck
+# ---------------------------------------------------------
+@app.get("/health")
+def health():
+    return {"status": "ok"}
+
+
+# ---------------------------------------------------------
+# Registrar routers
+# ---------------------------------------------------------
+app.include_router(researchers_router)
diff --git a/backend/app/repositories/publication_repository.py b/backend/app/repositories/publication_repository.py
new file mode 100644
index 0000000..2c64597
--- /dev/null
+++ b/backend/app/repositories/publication_repository.py
@@ -0,0 +1,67 @@
+from sqlalchemy.orm import Session
+from app.db.models import Publication
+
+
+class PublicationRepository:
+
+    @staticmethod
+    def get_by_put_code(db: Session, researcher_id: str, put_code: int):
+        """
+        Devuelve una publicación existente por put_code (único en ORCID).
+        """
+        return (
+            db.query(Publication)
+            .filter(
+                Publication.researcher_id == researcher_id,
+                Publication.put_code == put_code
+            )
+            .first()
+        )
+
+    @staticmethod
+    def create(db: Session, researcher_id: str, data: dict):
+        """
+        Crea una nueva publicación normalizada.
+        """
+        pub = Publication(
+            researcher_id=researcher_id,
+            put_code=data["put_code"],
+            title=data["title"],
+            journal=data["journal"],
+            doi=data["doi"],
+            pub_year=data["pub_year"],
+            type=data["type"],
+            hash_fingerprint=data["hash_fingerprint"]
+        )
+        db.add(pub)
+        db.commit()
+        db.refresh(pub)
+        return pub
+
+    @staticmethod
+    def update(db: Session, publication: Publication, data: dict):
+        """
+        Actualiza una publicación existente si ORCID ha cambiado algo.
+        """
+        publication.title = data["title"]
+        publication.journal = data["journal"]
+        publication.doi = data["doi"]
+        publication.pub_year = data["pub_year"]
+        publication.type = data["type"]
+        publication.hash_fingerprint = data["hash_fingerprint"]
+
+        db.commit()
+        db.refresh(publication)
+        return publication
+
+    @staticmethod
+    def list_by_researcher(db: Session, researcher_id: str):
+        """
+        Lista todas las publicaciones de un investigador.
+        """
+        return (
+            db.query(Publication)
+            .filter(Publication.researcher_id == researcher_id)
+            .order_by(Publication.pub_year.desc().nullslast())
+            .all()
+        )
diff --git a/backend/app/repositories/researcher_repository.py b/backend/app/repositories/researcher_repository.py
new file mode 100644
index 0000000..4aba7af
--- /dev/null
+++ b/backend/app/repositories/researcher_repository.py
@@ -0,0 +1,25 @@
+from sqlalchemy.orm import Session
+from app.db.models import Researcher
+from sqlalchemy.sql import func
+
+
+class ResearcherRepository:
+
+    @staticmethod
+    def get_by_orcid(db: Session, orcid_id: str):
+        return db.query(Researcher).filter(Researcher.orcid_id == orcid_id).first()
+
+    @staticmethod
+    def create(db: Session, orcid_id: str, name: str = None):
+        researcher = Researcher(orcid_id=orcid_id, name=name)
+        db.add(researcher)
+        db.commit()
+        db.refresh(researcher)
+        return researcher
+
+    @staticmethod
+    def update_last_sync(db: Session, researcher: Researcher):
+        researcher.last_sync_at = func.now()
+        db.commit()
+        db.refresh(researcher)
+        return researcher
diff --git a/backend/app/repositories/syncjob_repository.py b/backend/app/repositories/syncjob_repository.py
new file mode 100644
index 0000000..1cb00a1
--- /dev/null
+++ b/backend/app/repositories/syncjob_repository.py
@@ -0,0 +1,28 @@
+from sqlalchemy.orm import Session
+from app.db.models import SyncJob
+from sqlalchemy.sql import func
+
+
+class SyncJobRepository:
+
+    @staticmethod
+    def start_job(db: Session, researcher_id: str):
+        job = SyncJob(
+            researcher_id=researcher_id,
+            status="running",
+            started_at=func.now()
+        )
+        db.add(job)
+        db.commit()
+        db.refresh(job)
+        return job
+
+    @staticmethod
+    def finish_job(db: Session, job: SyncJob, new_records: int, updated_records: int):
+        job.status = "finished"
+        job.new_records = new_records
+        job.updated_records = updated_records
+        job.finished_at = func.now()
+        db.commit()
+        db.refresh(job)
+        return job
diff --git a/backend/app/schema/publication.py b/backend/app/schema/publication.py
new file mode 100644
index 0000000..b0d3710
--- /dev/null
+++ b/backend/app/schema/publication.py
@@ -0,0 +1,16 @@
+from pydantic import BaseModel
+from uuid import UUID
+
+class PublicationSchema(BaseModel):
+    id: UUID
+    put_code: int | None = None
+    title: str
+    journal: str | None = None
+    doi: str | None = None
+    pub_year: int | None = None
+    type: str | None = None
+    hash_fingerprint: str | None = None
+    last_modified: str | None = None
+
+    class Config:
+        from_attributes = True
diff --git a/backend/app/services/normalizer.py b/backend/app/services/normalizer.py
new file mode 100644
index 0000000..ee5c5b2
--- /dev/null
+++ b/backend/app/services/normalizer.py
@@ -0,0 +1,74 @@
+class PublicationNormalizer:
+
+    @staticmethod
+    def safe_get_title(summary):
+        t = summary.get("title")
+
+        if t is None:
+            return None
+
+        # Caso 1: {"title": {"value": "..."}}
+        if isinstance(t, dict) and "title" in t and isinstance(t["title"], dict):
+            return t["title"].get("value")
+
+        # Caso 2: {"title": {"title": "..."}} (muy común en /works)
+        if isinstance(t, dict) and "title" in t and isinstance(t["title"], str):
+            return t["title"]
+
+        # Caso 3: {"title": "string"}
+        if isinstance(t, str):
+            return t
+
+        # Caso 4: {"value": "..."}
+        if isinstance(t, dict) and "value" in t:
+            return t["value"]
+
+        return None
+
+    @staticmethod
+    def normalize_work(summary: dict) -> dict:
+
+        title = PublicationNormalizer.safe_get_title(summary)
+
+        # Journal title
+        journal_raw = summary.get("journal-title")
+        if isinstance(journal_raw, dict):
+            journal = journal_raw.get("value") or journal_raw.get("title")
+        else:
+            journal = journal_raw
+
+        # DOI
+        doi = None
+        ext_ids = summary.get("external-ids", {}).get("external-id", [])
+        for ext in ext_ids:
+            if ext.get("external-id-type") == "doi":
+                doi = ext.get("external-id-value")
+                break
+
+        # Publication year
+        pub_year = (
+            summary.get("publication-date", {})
+                   .get("year", {})
+                   .get("value")
+        )
+
+        # Type
+        work_type = summary.get("type")
+
+        # put-code
+        put_code = summary.get("put-code")
+
+        # Fingerprint
+        fingerprint = f"{title}-{doi}-{pub_year}-{work_type}"
+        if fingerprint:
+            fingerprint = fingerprint.lower().replace(" ", "")
+
+        return {
+            "put_code": put_code,
+            "title": title or "Untitled",
+            "journal": journal,
+            "doi": doi,
+            "pub_year": pub_year,
+            "type": work_type,
+            "hash_fingerprint": fingerprint
+        }
diff --git a/backend/app/services/orcid_client.py b/backend/app/services/orcid_client.py
index 45d6f79..068bf05 100644
--- a/backend/app/services/orcid_client.py
+++ b/backend/app/services/orcid_client.py
@@ -2,18 +2,13 @@ import httpx
 import os
 from typing import Optional
 
-
 class ORCIDClient:
-    """
-    Cliente para interactuar con la Public API de ORCID.
-    Permite:
-    - Obtener token público
-    - Consultar /record
-    - Consultar /works
-    """
+    
+    TOKEN_URL = "https://sandbox.orcid.org/oauth/token"
+    BASE_URL = "https://pub.sandbox.orcid.org/v3.0"
 
-    TOKEN_URL = "https://orcid.org/oauth/token"
-    BASE_URL = "https://pub.orcid.org/v3.0"
+    # TOKEN_URL = "https://orcid.org/oauth/token"
+    # BASE_URL = "https://pub.orcid.org/v3.0"
 
     def __init__(self):
         self.client_id = os.getenv("ORCID_CLIENT_ID")
diff --git a/backend/app/services/sword_exporter.py b/backend/app/services/sword_exporter.py
new file mode 100644
index 0000000..9912574
--- /dev/null
+++ b/backend/app/services/sword_exporter.py
@@ -0,0 +1,155 @@
+from datetime import datetime
+from xml.etree.ElementTree import Element, SubElement, tostring
+from io import BytesIO
+import zipfile
+import json
+
+
+class SWORDExporter:
+
+    ATOM_NS = "http://www.w3.org/2005/Atom"
+    DC_NS = "http://purl.org/dc/elements/1.1/"
+
+    # ---------------------------------------------------------
+    # 1) XML PRINCIPAL (sword.xml)
+    # ---------------------------------------------------------
+    @staticmethod
+    def export_feed_xml(researcher, publications) -> bytes:
+        feed = Element("feed", xmlns=SWORDExporter.ATOM_NS)
+
+        title = SubElement(feed, "title")
+        title.text = f"Publications for {researcher.orcid_id}"
+
+        author = SubElement(feed, "author")
+        name = SubElement(author, "name")
+        name.text = researcher.name or "Unknown"
+
+        updated = SubElement(feed, "updated")
+        updated.text = datetime.utcnow().isoformat() + "Z"
+
+        feed_id = SubElement(feed, "id")
+        feed_id.text = f"urn:uuid:{researcher.id}"
+
+        for pub in publications:
+            entry = SubElement(feed, "entry")
+
+            entry_id = SubElement(entry, "id")
+            entry_id.text = f"urn:uuid:{pub.id}"
+
+            entry_updated = SubElement(entry, "updated")
+            entry_updated.text = datetime.utcnow().isoformat() + "Z"
+
+            dc_title = SubElement(entry, f"{{{SWORDExporter.DC_NS}}}title")
+            dc_title.text = pub.title
+
+            if pub.doi:
+                dc_identifier = SubElement(entry, f"{{{SWORDExporter.DC_NS}}}identifier")
+                dc_identifier.text = f"doi:{pub.doi}"
+
+            if pub.pub_year:
+                dc_date = SubElement(entry, f"{{{SWORDExporter.DC_NS}}}date")
+                dc_date.text = str(pub.pub_year)
+
+            if pub.type:
+                dc_type = SubElement(entry, f"{{{SWORDExporter.DC_NS}}}type")
+                dc_type.text = pub.type
+
+            if pub.journal:
+                dc_source = SubElement(entry, f"{{{SWORDExporter.DC_NS}}}source")
+                dc_source.text = pub.journal
+
+        xml_bytes = tostring(feed, encoding="utf-8", xml_declaration=True)
+        return xml_bytes
+
+    # ---------------------------------------------------------
+    # 2) manifest.txt
+    # ---------------------------------------------------------
+    @staticmethod
+    def generate_manifest(researcher, publications) -> str:
+        lines = [
+            "SWORD Deposit Package",
+            "----------------------",
+            f"Researcher ORCID: {researcher.orcid_id}",
+            f"Researcher Name: {researcher.name or 'Unknown'}",
+            f"Total Publications: {len(publications)}",
+            f"Generated At: {datetime.utcnow().isoformat()}Z",
+            "",
+            "Publications:",
+        ]
+
+        for pub in publications:
+            lines.append(f"- {pub.title} ({pub.pub_year}) DOI={pub.doi}")
+
+        return "\n".join(lines)
+
+    # ---------------------------------------------------------
+    # 3) metadata.json
+    # ---------------------------------------------------------
+    @staticmethod
+    def generate_metadata_json(researcher, publications) -> str:
+        data = {
+            "researcher": {
+                "orcid_id": researcher.orcid_id,
+                "name": researcher.name,
+                "id": str(researcher.id),
+            },
+            "generated_at": datetime.utcnow().isoformat() + "Z",
+            "publications": [
+                {
+                    "id": str(pub.id),
+                    "title": pub.title,
+                    "doi": pub.doi,
+                    "year": pub.pub_year,
+                    "type": pub.type,
+                    "journal": pub.journal,
+                }
+                for pub in publications
+            ],
+        }
+        return json.dumps(data, indent=4)
+
+    # ---------------------------------------------------------
+    # 4) mets.xml (versión simple)
+    # ---------------------------------------------------------
+    @staticmethod
+    def generate_mets_xml(researcher, publications) -> bytes:
+        mets = Element("mets", xmlns="http://www.loc.gov/METS/")
+
+        header = SubElement(mets, "metsHdr")
+        agent = SubElement(header, "agent", ROLE="CREATOR", TYPE="OTHER")
+        name = SubElement(agent, "name")
+        name.text = "ORCID Exporter System"
+
+        dmd_sec = SubElement(mets, "dmdSec", ID="dmd1")
+        md_wrap = SubElement(dmd_sec, "mdWrap", MDTYPE="DC")
+        xml_data = SubElement(md_wrap, "xmlData")
+
+        for pub in publications:
+            dc_title = SubElement(xml_data, f"{{{SWORDExporter.DC_NS}}}title")
+            dc_title.text = pub.title
+
+            if pub.doi:
+                dc_id = SubElement(xml_data, f"{{{SWORDExporter.DC_NS}}}identifier")
+                dc_id.text = f"doi:{pub.doi}"
+
+        return tostring(mets, encoding="utf-8", xml_declaration=True)
+
+    # ---------------------------------------------------------
+    # 5) ZIP FINAL
+    # ---------------------------------------------------------
+    @staticmethod
+    def export_zip(researcher, publications) -> bytes:
+        xml_bytes = SWORDExporter.export_feed_xml(researcher, publications)
+        manifest = SWORDExporter.generate_manifest(researcher, publications)
+        metadata_json = SWORDExporter.generate_metadata_json(researcher, publications)
+        mets_xml = SWORDExporter.generate_mets_xml(researcher, publications)
+
+        mem_file = BytesIO()
+        with zipfile.ZipFile(mem_file, mode="w", compression=zipfile.ZIP_DEFLATED) as zf:
+            zf.writestr("sword.xml", xml_bytes)
+            zf.writestr("manifest.txt", manifest)
+            zf.writestr("metadata.json", metadata_json)
+            zf.writestr("mets.xml", mets_xml)
+
+        mem_file.seek(0)
+        return mem_file.read()
diff --git a/backend/app/services/sync_service.py b/backend/app/services/sync_service.py
new file mode 100644
index 0000000..b4477c5
--- /dev/null
+++ b/backend/app/services/sync_service.py
@@ -0,0 +1,96 @@
+from sqlalchemy.orm import Session
+from app.services.orcid_client import ORCIDClient
+from app.services.normalizer import PublicationNormalizer
+from app.repositories.researcher_repository import ResearcherRepository
+from app.repositories.publication_repository import PublicationRepository
+from app.repositories.syncjob_repository import SyncJobRepository
+import httpx
+
+
+class SyncService:
+
+    def __init__(self):
+        self.orcid_client = ORCIDClient()
+
+    def sync_researcher(self, db: Session, orcid_id: str):
+        """
+        Sincroniza las publicaciones de un investigador con manejo robusto de errores.
+        """
+
+        # 1. Obtener o crear investigador
+        try:
+            researcher = ResearcherRepository.get_by_orcid(db, orcid_id)
+
+            if not researcher:
+                record = self.orcid_client.fetch_record(orcid_id)
+                name = (
+                    record.get("person", {})
+                          .get("name", {})
+                          .get("given-names", {})
+                          .get("value")
+                )
+                researcher = ResearcherRepository.create(db, orcid_id, name)
+
+        except httpx.HTTPStatusError as e:
+            if e.response.status_code == 404:
+                return {
+                    "status": "error",
+                    "message": f"El ORCID {orcid_id} no existe en Sandbox."
+                }
+            return {"status": "error", "message": str(e)}
+
+        # 2. Crear SyncJob
+        job = SyncJobRepository.start_job(db, researcher.id)
+
+        # 3. Obtener works
+        try:
+            works_raw = self.orcid_client.fetch_works(orcid_id)
+        except httpx.HTTPStatusError as e:
+            if e.response.status_code == 404:
+                SyncJobRepository.finish_job(db, job, 0, 0)
+                ResearcherRepository.update_last_sync(db, researcher)
+                return {
+                    "status": "ok",
+                    "message": "El ORCID existe pero no tiene publicaciones públicas.",
+                    "new_records": 0,
+                    "updated_records": 0,
+                    "total": 0
+                }
+            return {"status": "error", "message": str(e)}
+
+        groups = works_raw.get("group", [])
+
+        new_records = 0
+        updated_records = 0
+
+        # 4. Procesar works
+        for group in groups:
+            summary = group["work-summary"][0]
+            normalized = PublicationNormalizer.normalize_work(summary)
+
+            # 🔥 AHORA SE DETECTAN DUPLICADOS POR put_code
+            existing = PublicationRepository.get_by_put_code(
+                db, researcher.id, normalized["put_code"]
+            )
+
+            if existing:
+                PublicationRepository.update(db, existing, normalized)
+                updated_records += 1
+            else:
+                PublicationRepository.create(db, researcher.id, normalized)
+                new_records += 1
+
+        # 5. Finalizar SyncJob
+        SyncJobRepository.finish_job(db, job, new_records, updated_records)
+
+        # 6. Actualizar last_sync_at
+        ResearcherRepository.update_last_sync(db, researcher)
+
+        return {
+            "status": "ok",
+            "message": "Sincronización completada correctamente.",
+            "researcher": researcher.orcid_id,
+            "new_records": new_records,
+            "updated_records": updated_records,
+            "total": new_records + updated_records
+        }
diff --git a/backend/app/utils/orcid_validator.py b/backend/app/utils/orcid_validator.py
new file mode 100644
index 0000000..235a88b
--- /dev/null
+++ b/backend/app/utils/orcid_validator.py
@@ -0,0 +1,28 @@
+import re
+
+ORCID_REGEX = re.compile(r"^\d{4}-\d{4}-\d{4}-\d{3}[0-9X]$")
+
+
+def is_valid_orcid(orcid_id: str) -> bool:
+    """
+    Valida un ORCID ID:
+    - Formato: 0000-0000-0000-0000
+    - Dígito de control según ISO 7064 Mod 11-2
+    """
+    if not ORCID_REGEX.match(orcid_id):
+        return False
+
+    # Quitar guiones
+    digits = orcid_id.replace("-", "")
+
+    total = 0
+    # Los primeros 15 dígitos
+    for char in digits[:-1]:
+        total = (total + int(char)) * 2
+
+    # Resto
+    remainder = total % 11
+    result = (12 - remainder) % 11
+    check_digit = "X" if result == 10 else str(result)
+
+    return digits[-1] == check_digit