URL Encoding Automation Errors: Why Marketing Tools Double-Encode UTMs

// HubSpot workflow action: "Create tracking URL"
 
Input (from CRM):
contact.campaign = "Webinar: Marketing Tips"
 
Workflow encodes:
encodedCampaign = "Webinar%3A%20Marketing%20Tips"
 
Your workflow template (already encoded):
"https://example.com?utm_campaign={"{"}{"{"}encodedCampaign{"}"}{"}"}}"
 
HubSpot sees % and encodes AGAIN:
Result: "...?utm_campaign=Webinar%253A%2520Marketing%2520Tips"

// ❌ DON'T send encoded URLs to Bitly
const encodedURL = `https://example.com?utm_campaign=${encodeURIComponent('summer sale')}`;
await bitly.shorten(encodedURL);  // Will double-encode!
 
// ✅ DO send clean URLs
const cleanURL = 'https://example.com?utm_campaign=summer-sale';
await bitly.shorten(cleanURL);  // No encoding needed!

<!-- Marketo form with hidden UTM fields -->
<form>
  <input type="hidden" name="utm_campaign" value="{{my.Campaign Name}}" />
</form>
 
{{my.Campaign Name}} = "Q4 Webinar Series"
 
Marketo inserts: value="Q4 Webinar Series"
Browser form-encodes: Q4+Webinar+Series
Marketo receives and re-encodes: Q4%2BWeber%2BSeries
 
Result: "Q4+Webinar+Series" in analytics (with literal +)

<!-- Use URL-safe token -->
<input type="hidden" name="utm_campaign" value="{{my.Campaign Slug}}" />
 
Where Campaign Slug = "q4-webinar-series"

// Step 2: Don't encode, just clean
function cleanCampaign(value) {
  return value
    .toLowerCase()
    .replace(/\s+/g, '-')
    .replace(/[^a-z0-9-_]/g, '');
}
 
// Use: cleanCampaign("Summer Sale") → "summer-sale"
// No encoding needed anywhere!

# Python script sending to API
 
import requests
from urllib.parse import urlencode
 
# Create UTM parameters
params = {
    'utm_campaign': 'Summer Sale'
}
 
# Encode manually
encoded_params = urlencode(params)
# Result: 'utm_campaign=Summer+Sale'
 
# Pass to email API
url = f"https://example.com?`{"{"}{"{"}encoded_params{"}"}{"}"}}`"
response = requests.get(url)
# requests library encodes AGAIN
# Final: utm_campaign=Summer%2BSale
 
# Analytics shows: "Summer+Sale" (literal +)

# ❌ DON'T encode before passing
params = {'utm_campaign': 'Summer Sale'}
encoded = urlencode(params)  # Encoded once
requests.get(url, params=encoded)  # Encoded twice!
 
# ✅ DO use clean values
params = {'utm_campaign': 'summer-sale'}
requests.get(url, params=params)  # No encoding needed

async function testAutomationEncoding(automationTool, testCampaign) {
  console.log(`\nTesting: ${automationTool.name}`);
  console.log(`Input: "${"{"}{"{"}testCampaign{"}"}{"}"}}"`);
 
  // Step 1: Submit to automation
  const url = await automationTool.generateURL({
    utm_campaign: testCampaign
  });
 
  console.log(`Generated URL: ${"{"}{"{"}url{"}"}{"}"}}`);
 
  // Step 2: Parse result
  const urlObj = new URL(url);
  const campaign = urlObj.searchParams.get('utm_campaign');
 
  console.log(`Campaign parameter: "${"{"}{"{"}campaign{"}"}{"}"}}"`);
 
  // Step 3: Check for encoding
  if (campaign.includes('%')) {
    // Try decoding
    const decoded = decodeURIComponent(campaign);
    console.log(`Decoded once: "${"{"}{"{"}decoded{"}"}{"}"}}"`);
 
    if (decoded !== campaign) {
      // Check if double-encoded
      const decodedTwice = decodeURIComponent(decoded);
      if (decodedTwice !== decoded) {
        console.log(`❌ DOUBLE-ENCODING DETECTED!`);
        console.log(`Original input: "${"{"}{"{"}testCampaign{"}"}{"}"}}"`);
        console.log(`After automation: "${"{"}{"{"}campaign{"}"}{"}"}}"`);
        console.log(`Decoded once: "${"{"}{"{"}decoded{"}"}{"}"}}"`);
        console.log(`Decoded twice: "${"{"}{"{"}decodedTwice{"}"}{"}"}}"`);
        return {
          tool: automationTool.name,
          doubleEncoded: true,
          evidence: { input: testCampaign, output: campaign, decoded, decodedTwice }
        };
      }
    }
 
    console.log(`⚠️ Single-encoded (should use clean values instead)`);
    return {
      tool: automationTool.name,
      doubleEncoded: false,
      singleEncoded: true
    };
  }
 
  console.log(`✅ No encoding (good!)`);
  return {
    tool: automationTool.name,
    doubleEncoded: false,
    singleEncoded: false
  };
}
 
// Test your automation
const testResults = await testAutomationEncoding(mailchimpAdapter, 'Summer Sale 2024');

// Test Bitly
const testURL = 'https://example.com?utm_campaign=test-campaign';
const shortLink = await bitly.shorten(testURL);
const destination = await bitly.getDestination(shortLink);
 
console.log('Input:', testURL);
console.log('Destination:', destination);
 
if (destination !== testURL) {
  console.log('❌ URL changed! Check for encoding differences.');
}

// Universal rule: Never encode values yourself
 
// ❌ DON'T:
const campaign = encodeURIComponent('Summer Sale');
 
// ✅ DO:
const campaign = 'summer-sale';
 
// Let tools handle encoding if needed (they usually won't need to)

function validateNoEncoding(url, stepName) {
  if (url.match(/\?.*%[0-9A-Fa-f]{2}/)) {
    throw new Error(`Encoding detected at step: ${"{"}{"{"}stepName{"}"}{"}"}}\nURL: ${"{"}{"{"}url{"}"}{"}"}}`);
  }
 
  return url;
}
 
// Use between automation steps
let url = generateBaseURL();
url = validateNoEncoding(url, 'Initial generation');
 
url = addToEmailTemplate(url);
url = validateNoEncoding(url, 'After email template');
 
url = shortenURL(url);
url = validateNoEncoding(url, 'After shortening');

async function testCompleteWorkflow() {
  const testCampaign = 'test-automation-encoding';
 
  // Generate URL
  const url = buildURL({ utm_campaign: testCampaign });
 
  // Step through automation
  const emailURL = await emailPlatform.process(url);
  const shortURL = await urlShortener.create(emailURL);
  const finalURL = await urlShortener.resolve(shortURL);
 
  // Validate final result
  const finalCampaign = new URL(finalURL).searchParams.get('utm_campaign');
 
  if (finalCampaign !== testCampaign) {
    throw new Error(`Workflow changed campaign value!\nExpected: ${"{"}{"{"}testCampaign{"}"}{"}"}}\nGot: ${"{"}{"{"}finalCampaign{"}"}{"}"}}`);
  }
 
  console.log('✅ Workflow validated successfully');
}