This guide walks through a free tracking stack — UTM-tagged links, Google Analytics 4, unique referral codes, and a shared spreadsheet — that tells you who’s referring, how many clicks they’re generating, and whether those clicks turn into customers.

Quick Answer

You can track referral performance without paid software by combining UTM-tagged links with Google Analytics 4’s Traffic Acquisition report, giving each referrer a unique code or link, and logging everything in a shared Google Sheet. This gives you clicks, sources, and conversions for a small or early-stage referral program at no cost.

Build Your Free Tracking Stack With UTM Links and GA4

Start by creating a UTM-tagged link for every referral channel or individual referrer using Google’s free Campaign URL Builder. Use utm_source to identify the specific referrer or channel (a customer’s name, a partner site, a newsletter) and keep utm_medium consistent — set it to “referral” every time, always in lowercase. GA4’s source/medium reporting is case sensitive, so inconsistent capitalization (“referral” vs. “Referral”) can cause the same referrer’s traffic to be split across separate rows instead of totaled together.

Keep your UTM values in a locked reference tab in Google Sheets (approved sources, approved mediums) so everyone tagging links uses the same spelling and casing. Then check performance in GA4 under Reports > Acquisition > Traffic Acquisition, filtering or breaking down by session source/medium to see which referrers are driving traffic.

To see whether that traffic actually converts, set up a conversion event in GA4 for whatever counts as success — a purchase, a signup, a booked call. Traffic Acquisition then shows conversions per source, not just clicks, which is the number that actually matters for a referral program.

Use Unique Codes and a Spreadsheet as Your System of Record

If you sell through Shopify or WooCommerce, you don’t need referral software to attribute sales — give each participant a unique discount code instead. Shopify and WooCommerce both generate redemption reports per coupon code natively, so you can see exactly how many orders came from each referrer’s code without installing anything extra.

Maintain one Google Sheet as your master campaign log, with columns for referrer name, their unique code or UTM link, date issued, clicks (pulled from GA4), conversions, and reward status. For service or B2B businesses without ecommerce coupons, a simple Google Form asking new customers “who referred you?” feeds straight into this sheet, and a Zapier connection can automate that handoff so entries land in the spreadsheet without manual copy-pasting.

This combination — UTM/GA4 for click-level data, unique codes for purchase-level attribution, and a spreadsheet tying it together — covers the two questions a referral program needs answered: is anyone sharing this, and is it generating revenue?

Tips and Common Mistakes

Standardize your utm_medium value, in lowercase, before you tag a single link. Going back and fixing inconsistent tagging after the fact means messy historical data you can’t fully recover.

Don’t lean on Bitly’s free plan as a tracking tool. Its free tier is limited on monthly link creation and doesn’t include the click analytics you’d need to measure referral performance. UTM parameters plus GA4 give you real click and conversion data for free instead.

Separate clicks from conversions in your reporting. A referrer can generate plenty of link clicks that never turn into a sale, so always cross-check GA4 traffic against actual coupon redemptions or your CRM/order data before crediting a reward.

Reconcile the spreadsheet on a fixed cadence — weekly or monthly — rather than trying to keep it live. Manual tracking only stays useful if you build the habit of updating it.

Treat this stack as a validation phase. Once you have enough referrers that manual reconciliation becomes a bottleneck, or you need real-time reward payouts, that’s the signal you’ve outgrown spreadsheets and it’s worth evaluating dedicated referral software.

Explore more: more referral marketing guides.

Free referral program tracking FAQs

What’s the cheapest way to track who referred a sale?

Give each referrer a unique discount code or UTM-tagged link, then check redemptions in your store’s coupon report or check conversions in GA4. Both approaches are free and use tools most businesses already have.

Does Google Analytics 4 track referrals automatically?

GA4 automatically labels traffic arriving from other websites as “referral” medium when referrer data is available, but for your own referral program you should manually tag each referrer’s link with UTM parameters so their traffic is broken out individually instead of lumped into one generic referral bucket.

Is Bitly good for tracking referral link clicks for free?

Not really. Bitly’s free plan limits how many links you can create each month and doesn’t include the click analytics you’d need for referral tracking, so it’s not a reliable free option. UTM parameters combined with GA4’s Traffic Acquisition report cover the same need at no cost.

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Photo by Luke Chesser on Unsplash.