PDF Editing

import fitz

doc = fitz.open("input.pdf")
page = doc[0]

# 1. First find what value is in the PDF by reading the text
pdf_text = page.get_text()
# Find the ID in the text (e.g., "A88888888")

original_in_pdf = "A88888888"  # Value you found in the PDF
# Extract just the digits for masking
digits = ''.join(c for c in original_in_pdf if c.isdigit())
masked = "****" + digits[-4:]  # Result: "****8888"

rects = page.search_for(original_in_pdf)
if rects:
    rect = rects[0]

    # STEP 1: Create TIGHT bounding box to avoid covering nearby labels
    tight_rect = fitz.Rect(rect.x0, rect.y0 + 8, rect.x1, rect.y1 - 2)

    # STEP 2: Add redaction annotation with WHITE fill (not black!)
    page.add_redact_annot(tight_rect, fill=(1, 1, 1))  # WHITE fill

    # STEP 2: Apply redactions - this REMOVES the text from PDF structure
    page.apply_redactions()

    # STEP 3: Insert masked value at the same position
    page.insert_text((rect.x0, rect.y1), masked, fontsize=11, color=(0, 0, 0))

doc.save("output.pdf")

# WRONG: Black box redaction (ugly and suspicious)
page.add_redact_annot(rect, fill=(0, 0, 0))  # NO! Use white fill

# WRONG: Only using draw_rect (text still extractable!)
page.draw_rect(rect, fill=(1, 1, 1))  # NO! This only covers visually
page.insert_text(...)  # Original text is still in PDF structure!

# WRONG: Adding masked value NEXT TO original
page.insert_text((rect.x1 + 10, rect.y1), masked)  # NO!

import fitz

doc = fitz.open("input.pdf")
page = doc[0]

# Step 1: Read PDF to see current content
pdf_text = page.get_text()
print(pdf_text)

# Step 2: Read your input source to get correct values
# (parse input file, extract the values you need)

# Step 3: For each value that differs, replace it
# Build a dict of {old_value_in_pdf: correct_value}
replacements = {}  # Populate by comparing PDF content with correct values

for old_val, new_val in replacements.items():
    if old_val == new_val:
        continue  # Skip if already correct
    rects = page.search_for(old_val)
    if rects:
        rect = rects[0]
        # Cover old text with white rectangle
        page.draw_rect(rect, color=(1, 1, 1), fill=(1, 1, 1), width=0)
        # Insert new text
        page.insert_text((rect.x0, rect.y1), new_val, fontsize=11, color=(0, 0, 0))

doc.save("output.pdf")

const { PDFDocument, rgb } = require('pdf-lib');
const fs = require('fs');

async function editPdf() {
  const pdfBytes = fs.readFileSync('input.pdf');
  const pdfDoc = await PDFDocument.load(pdfBytes);
  const page = pdfDoc.getPages()[0];
  const { height } = page.getSize();

  // To replace text at known coordinates:
  // STEP 1: Draw WHITE rectangle to cover old text
  page.drawRectangle({
    x: oldTextX,
    y: oldTextY,
    width: oldTextWidth,
    height: oldTextHeight,
    color: rgb(1, 1, 1),  // WHITE
  });

  // STEP 2: Draw new text at the SAME position
  page.drawText('New Value', {
    x: oldTextX,  // SAME X position, not offset!
    y: oldTextY,
    size: 11,
    color: rgb(0, 0, 0),
  });

  fs.writeFileSync('output.pdf', await pdfDoc.save());
}

// WRONG: Adding text to the right of old value
page.drawText('New Value', {
  x: oldTextX + oldTextWidth + 10,  // NO! Don't offset
  ...
});

// WRONG: Drawing strikethrough line
page.drawLine({
  start: { x: x1, y: y },
  end: { x: x2, y: y },
  color: rgb(0, 0, 0),  // NO strikethrough!
});