URL Encoding for Marketers: UTM Parameters, Tracking Links & Redirects

September 5, 2026 · 4 min read

A broken tracking link means lost data. If your UTM parameters are not properly encoded, Google Analytics may not capture your campaign data, and your attribution reporting falls apart. Understanding basic URL encoding prevents these invisible but costly mistakes in your marketing campaigns.

UTM Parameters and Special Characters

UTM parameters are appended to URLs: ?utm_source=facebook&utm_medium=cpc&utm_campaign=summer_sale. If your campaign name contains spaces or special characters (Summer Sale 2026 — 20% Off), you must encode them: utm_campaign=Summer%20Sale%202026%20%E2%80%94%2020%25%20Off. Unencoded special characters break the URL.

Affiliate Link Encoding

Many affiliate programs pass the destination URL as a parameter: affiliate.com/go?url=https://store.com/product?id=123&color=blue. The & in the destination URL conflicts with the affiliate URL structure. You must encode the entire destination URL so the affiliate platform passes it through correctly.

Redirect Chain Issues

When a URL passes through multiple redirects (ad platform → tracking tool → landing page), each redirect may encode or decode the URL. Double-encoded URLs (%2520 instead of %20) are a common result. Test your full redirect chain end-to-end before launching a campaign.

QR Codes and URL Encoding

When generating QR codes for URLs with parameters, the URL must be properly encoded. A QR code scanner reads the raw data — if special characters are not encoded, the scanned URL may break. Always test QR codes by scanning them yourself before printing.

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Also useful: our QR Code Generator for related calculations.