diff --git a/app/routers/__pycache__/companies.cpython-312.pyc b/app/routers/__pycache__/companies.cpython-312.pyc
index 2ab18c8..d1b4558 100644
Binary files a/app/routers/__pycache__/companies.cpython-312.pyc and b/app/routers/__pycache__/companies.cpython-312.pyc differ
diff --git a/app/routers/__pycache__/investors.cpython-312.pyc b/app/routers/__pycache__/investors.cpython-312.pyc
index 0c21826..1416da7 100644
Binary files a/app/routers/__pycache__/investors.cpython-312.pyc and b/app/routers/__pycache__/investors.cpython-312.pyc differ
diff --git a/app/routers/companies.py b/app/routers/companies.py
index 3e83c3a..626c080 100644
--- a/app/routers/companies.py
+++ b/app/routers/companies.py
@@ -34,6 +34,10 @@ def read_companies(db: Session = Depends(get_db)):
     """Get all companies with their investor relationships"""
     companies = (
         db.query(CompanyTable)
+        .filter(
+            CompanyTable.name.isnot(None),
+            CompanyTable.description.isnot(None)
+        )
         .options(
             selectinload(CompanyTable.investors),
             selectinload(CompanyTable.members),
diff --git a/app/routers/investors.py b/app/routers/investors.py
index d7078fc..b28b532 100644
--- a/app/routers/investors.py
+++ b/app/routers/investors.py
@@ -7,6 +7,7 @@ from fastapi import APIRouter, Depends, HTTPException, Query
 from schemas.router_schemas import InvestmentStage, InvestorData
 from pydantic import BaseModel
 from sqlalchemy.orm import Session, selectinload
+from services.querying import QueryProcessor
 
 router = APIRouter(tags=["Investor Routes"])
 
@@ -234,3 +235,70 @@ def delete_investor(investor_id: int, db: Session = Depends(get_db)):
     return {"message": "Investor deleted successfully"}
 
 
+@router.get("/investors/{investor_id}/similar", response_model=List[InvestorData])
+def find_similar_investors(investor_id: int, db: Session = Depends(get_db)):
+    """Find investors similar to a given investor"""
+    
+    # First, get the target investor
+    target_investor = (
+        db.query(InvestorTable)
+        .options(
+            selectinload(InvestorTable.portfolio_companies),
+            selectinload(InvestorTable.team_members),
+            selectinload(InvestorTable.sectors),
+        )
+        .filter(InvestorTable.id == investor_id)
+        .first()
+    )
+    
+    if not target_investor:
+        raise HTTPException(status_code=404, detail="Investor not found")
+    
+    # Build query to find similar investors
+    query = db.query(InvestorTable).options(
+        selectinload(InvestorTable.portfolio_companies),
+        selectinload(InvestorTable.team_members),
+        selectinload(InvestorTable.sectors),
+    ).filter(InvestorTable.id != investor_id)  # Exclude the target investor
+    
+    # Filter by same stage focus
+    query = query.filter(InvestorTable.stage_focus == target_investor.stage_focus)
+    
+    # Filter by similar geographic focus (partial match)
+    query = query.filter(InvestorTable.geographic_focus.ilike(f"%{target_investor.geographic_focus}%"))
+    
+    # Filter by overlapping check size ranges
+    query = query.filter(
+        InvestorTable.check_size_upper >= target_investor.check_size_lower,
+        InvestorTable.check_size_lower <= target_investor.check_size_upper
+    )
+    
+    # Filter by similar AUM (within 50% range)
+    aum_lower = int(target_investor.aum * 0.5)
+    aum_upper = int(target_investor.aum * 1.5)
+    query = query.filter(
+        InvestorTable.aum >= aum_lower,
+        InvestorTable.aum <= aum_upper
+    )
+    
+    # Filter by common sectors
+    target_sector_names = [sector.name for sector in target_investor.sectors]
+    if target_sector_names:
+        query = query.join(InvestorTable.sectors).filter(
+            SectorTable.name.in_(target_sector_names)
+        )
+    
+    investors = query.all()
+    
+    # Transform to InvestorData format
+    investor_data_list = []
+    for investor in investors:
+        investor_data = InvestorData(
+            investor=investor,
+            portfolio_companies=investor.portfolio_companies,
+            team_members=investor.team_members,
+            sectors=investor.sectors,
+        )
+        investor_data_list.append(investor_data)
+    
+    return investor_data_list
\ No newline at end of file
diff --git a/app/schemas/__pycache__/py_schemas.cpython-312.pyc b/app/schemas/__pycache__/py_schemas.cpython-312.pyc
index 9dd3893..d8c9844 100644
Binary files a/app/schemas/__pycache__/py_schemas.cpython-312.pyc and b/app/schemas/__pycache__/py_schemas.cpython-312.pyc differ
diff --git a/app/schemas/py_schemas.py b/app/schemas/py_schemas.py
index 4fa88ec..5b982fa 100644
--- a/app/schemas/py_schemas.py
+++ b/app/schemas/py_schemas.py
@@ -19,13 +19,32 @@ class SectorSchema(BaseModel):
     Leave name empty if uncertain about the sector classification.
     """
 
-    id: int = Field(
-        ge=0, description="Sector ID, must be 0 or greater. Use 0 if uncertain."
+    id: Optional[int] = Field(
+        default=None,
+        ge=0,
+        description="Sector ID, must be 0 or greater. Use 0 if uncertain.",
     )
-    name: str = Field(
-        description="Sector name. Leave empty string if not clearly identifiable from the data."
+    name: Optional[str] = Field(
+        default=None,
+        description="Sector name. Leave empty string if not clearly identifiable from the data.",
     )
 
+    @field_validator("name", mode="before")
+    @classmethod
+    def empty_string_to_none(cls, v):
+        """Convert empty strings to None"""
+        if v == "" or (isinstance(v, str) and v.strip() == ""):
+            return None
+        return v
+
+    @field_validator("id", mode="before")
+    @classmethod
+    def zero_to_none(cls, v):
+        """Convert 0 to None for optional id field"""
+        if v == 0:
+            return None
+        return v
+
     class Config:
         from_attributes = True
 
@@ -36,22 +55,45 @@ class InvestorMemberSchema(BaseModel):
     Leave fields empty if uncertain about the member details.
     """
 
-    id: int = Field(
-        ge=0, description="Member ID, must be 0 or greater. Use 0 if uncertain."
+    id: Optional[int] = Field(
+        default=None,
+        ge=0,
+        description="Member ID, must be 0 or greater. Use 0 if uncertain.",
     )
-    name: str = Field(
-        description="Team member name. Leave empty string if not clearly identifiable."
+    name: Optional[str] = Field(
+        default=None,
+        description="Team member name. Leave empty string if not clearly identifiable.",
     )
-    role: str = Field(
-        description="Team member role/title. Leave empty string if not clearly identifiable."
+    role: Optional[str] = Field(
+        default=None,
+        description="Team member role/title. Leave empty string if not clearly identifiable.",
     )
-    email: str = Field(
-        description="Team member email. Leave empty string if not clearly identifiable or not provided."
+    email: Optional[str] = Field(
+        default=None,
+        description="Team member email. Leave empty string if not clearly identifiable or not provided.",
     )
-    investor_id: int = Field(
-        ge=0, description="Investor ID, must be 0 or greater. Use 0 if uncertain."
+    investor_id: Optional[int] = Field(
+        default=None,
+        ge=0,
+        description="Investor ID, must be 0 or greater. Use 0 if uncertain.",
     )
 
+    @field_validator("name", "role", "email", mode="before")
+    @classmethod
+    def empty_string_to_none(cls, v):
+        """Convert empty strings to None"""
+        if v == "" or (isinstance(v, str) and v.strip() == ""):
+            return None
+        return v
+
+    @field_validator("id", "investor_id", mode="before")
+    @classmethod
+    def zero_to_none(cls, v):
+        """Convert 0 to None for optional integer fields"""
+        if v == 0:
+            return None
+        return v
+
     class Config:
         from_attributes = True
 
@@ -62,25 +104,45 @@ class CompanyMemberSchema(BaseModel):
     Leave fields empty if uncertain about the member details.
     """
 
-    id: int = Field(
-        ge=0, description="Member ID, must be 0 or greater. Use 0 if uncertain."
+    id: Optional[int] = Field(
+        default=None,
+        ge=0,
+        description="Member ID, must be 0 or greater. Use 0 if uncertain.",
     )
     name: Optional[str] = Field(
-        default="",
+        default=None,
         description="Company member name. Leave empty if not clearly identifiable.",
     )
     linkedin: Optional[str] = Field(
-        default="",
+        default=None,
         description="LinkedIn profile URL. Leave empty if not provided or uncertain.",
     )
     role: Optional[str] = Field(
-        default="",
+        default=None,
         description="Company member role/title. Leave empty if not clearly identifiable.",
     )
-    company_id: int = Field(
-        ge=0, description="Company ID, must be 0 or greater. Use 0 if uncertain."
+    company_id: Optional[int] = Field(
+        default=None,
+        ge=0,
+        description="Company ID, must be 0 or greater. Use 0 if uncertain.",
     )
 
+    @field_validator("name", "linkedin", "role", mode="before")
+    @classmethod
+    def empty_string_to_none(cls, v):
+        """Convert empty strings to None"""
+        if v == "" or (isinstance(v, str) and v.strip() == ""):
+            return None
+        return v
+
+    @field_validator("id", "company_id", mode="before")
+    @classmethod
+    def zero_to_none(cls, v):
+        """Convert 0 to None for optional integer fields"""
+        if v == 0:
+            return None
+        return v
+
     class Config:
         from_attributes = True
 
@@ -91,20 +153,25 @@ class CompanySchema(BaseModel):
     Leave optional fields empty if uncertain. Integer values must be 0 or greater.
     """
 
-    id: int = Field(
-        ge=0, description="Company ID, must be 0 or greater. Use 0 if uncertain."
+    id: Optional[int] = Field(
+        default=None,
+        ge=0,
+        description="Company ID, must be 0 or greater. Use 0 if uncertain.",
     )
-    name: str = Field(
-        description="Company name. Leave empty string if not clearly identifiable."
+    name: Optional[str] = Field(
+        default=None,
+        description="Company name. Leave empty string if not clearly identifiable.",
     )
-    industry: str = Field(
-        description="Company industry/sector. Leave empty string if not clearly identifiable."
+    industry: Optional[str] = Field(
+        default=None,
+        description="Company industry/sector. Leave empty string if not clearly identifiable.",
     )
-    location: str = Field(
-        description="Company location/address. Leave empty string if not clearly identifiable."
+    location: Optional[str] = Field(
+        default=None,
+        description="Company location/address. Leave empty string if not clearly identifiable.",
     )
     description: Optional[str] = Field(
-        default="",
+        default=None,
         description="Company description. Leave empty if not clearly available or uncertain.",
     )
     founded_year: Optional[int] = Field(
@@ -113,10 +180,28 @@ class CompanySchema(BaseModel):
         description="Year company was founded, must be 0 or greater. Leave None if not clearly identifiable or uncertain.",
     )
     website: Optional[str] = Field(
-        default="",
+        default=None,
         description="Company website URL. Leave empty if not provided or uncertain.",
     )
 
+    @field_validator(
+        "name", "industry", "location", "description", "website", mode="before"
+    )
+    @classmethod
+    def empty_string_to_none(cls, v):
+        """Convert empty strings to None"""
+        if v == "" or (isinstance(v, str) and v.strip() == ""):
+            return None
+        return v
+
+    @field_validator("id", "founded_year", mode="before")
+    @classmethod
+    def zero_to_none(cls, v):
+        """Convert 0 to None for founded_year"""
+        if v == 0:
+            return None
+        return v
+
     @field_validator("founded_year", mode="before")
     @classmethod
     def validate_founded_year(cls, v):
@@ -141,40 +226,71 @@ class InvestorSchema(BaseModel):
     Leave optional fields empty if uncertain. All numeric values must be 0 or greater.
     """
 
-    id: int = Field(
-        ge=0, description="Investor ID, must be 0 or greater. Use 0 if uncertain."
+    id: Optional[int] = Field(
+        default=None,
+        ge=0,
+        description="Investor ID, must be 0 or greater. Use 0 if uncertain.",
     )
-    name: str = Field(
-        description="Investor name. Do not return any special characters, Just the name as a string."
+    name: Optional[str] = Field(
+        default=None,
+        description="Investor name. Do not return any special characters, Just the name as a string.",
     )
     description: Optional[str] = Field(
-        default="",
+        default=None,
         description="Investor description. Leave empty if not clearly available or uncertain.",
     )
-    aum: int | None = Field(
+    aum: Optional[int] = Field(
+        default=None,
         ge=0,
         description="Assets Under Management in USD, must be 0 or greater. Use 0 if not clearly identifiable or uncertain.",
     )
-    check_size_lower: int | None = Field(
+    check_size_lower: Optional[int] = Field(
+        default=None,
         ge=0,
         description="Lower bound of typical investment check size in USD, must be 0 or greater. Use 0 if not clearly identifiable.",
     )
-    check_size_upper: int | None = Field(
+    check_size_upper: Optional[int] = Field(
+        default=None,
         ge=0,
         description="Upper bound of typical investment check size in USD, must be 0 or greater. Use 0 if not clearly identifiable.",
     )
-    geographic_focus: str | None = Field(
+    geographic_focus: Optional[str] = Field(
+        default=None,
         description="Geographic investment focus. Do not return any special characters, Just locations separated by commas. Leave empty if not clearly identifiable.",
     )
     stage_focus: InvestmentStage = Field(
-        description="Investment stage focus. Use SEED as default if uncertain."
+        default=InvestmentStage.SEED,
+        description="Investment stage focus. Use SEED as default if uncertain.",
     )
-    number_of_investments: int | None = Field(
+    number_of_investments: Optional[int] = Field(
+        default=None,
         ge=0,
-        default=0,
         description="Total number of investments made, must be 0 or greater. Use 0 if not clearly identifiable.",
     )
 
+    @field_validator("name", "description", "geographic_focus", mode="before")
+    @classmethod
+    def empty_string_to_none(cls, v):
+        """Convert empty strings to None"""
+        if v == "" or (isinstance(v, str) and v.strip() == ""):
+            return None
+        return v
+
+    @field_validator(
+        "id",
+        "aum",
+        "check_size_lower",
+        "check_size_upper",
+        "number_of_investments",
+        mode="before",
+    )
+    @classmethod
+    def zero_to_none(cls, v):
+        """Convert 0 to None for optional integer fields"""
+        if v == 0:
+            return None
+        return v
+
     class Config:
         from_attributes = True
 
diff --git a/app/services/__pycache__/llm_parser.cpython-312.pyc b/app/services/__pycache__/llm_parser.cpython-312.pyc
index e64b117..7e4223f 100644
Binary files a/app/services/__pycache__/llm_parser.cpython-312.pyc and b/app/services/__pycache__/llm_parser.cpython-312.pyc differ
diff --git a/app/services/__pycache__/querying.cpython-312.pyc b/app/services/__pycache__/querying.cpython-312.pyc
index cadd1a4..fb5cb6d 100644
Binary files a/app/services/__pycache__/querying.cpython-312.pyc and b/app/services/__pycache__/querying.cpython-312.pyc differ
diff --git a/app/services/llm_parser.py b/app/services/llm_parser.py
index 0387a6c..bc714f2 100644
--- a/app/services/llm_parser.py
+++ b/app/services/llm_parser.py
@@ -21,7 +21,7 @@ class InvestorProcessor:
         self.llm = ChatOpenAI(
             api_key=os.getenv("OPENROUTER_API_KEY"),
             base_url="https://openrouter.ai/api/v1",
-            model="google/gemini-2.5-flash-lite",
+            model="openai/gpt-4o-mini",
             temperature=0,
         )
 
diff --git a/app/services/querying.py b/app/services/querying.py
index 11b38f4..3078e18 100644
--- a/app/services/querying.py
+++ b/app/services/querying.py
@@ -21,8 +21,8 @@ class QueryProcessor:
         self.llm = ChatOpenAI(
             api_key=os.getenv("OPENROUTER_API_KEY"),
             base_url="https://openrouter.ai/api/v1",
-            model="openai/gpt-5-nano",
-            temperature=0.3,
+            model="openai/gpt-4o-mini",
+            temperature=0,
         )
         self.toolkit = SQLDatabaseToolkit(db=db, llm=self.llm)
         # Update system message to specifically request only investor IDs