Google Analytics is excellent at what it does. Tell you how many people visited, where they came from at a population level, and how they moved through the site. You should keep it.
What GA was never built to do is tell you which actual customer came from which actual ad. That’s the question your spend reviews need answered, and it’s the question Lead Source exists to answer. Different tools, different jobs.
The capabilities, without the spin
Where each tool wins, where they overlap, and where they don’t.
| Capability | Google Analytics | Lead Source |
|---|---|---|
| Traffic & audience | ||
| Pageviews, sessions, bounce rate | Yes | No |
| Real-time visitor count | Yes | No |
| Audience demographics, interests, devices | Yes | No |
| Site search, scroll depth, engagement events | Yes | No |
| Lead identity & attribution | ||
| Captures the actual person who filled out a form | No | Yes |
| Notifies you when a lead converts, by source | No | Yes |
| Writes source attribution into your CRM contact | No | Yes |
| Captures the full page journey before submit | Partial (paths in reports) | Per-lead, attached |
| Captures form field data alongside source | No | Yes |
| Reliability | ||
| Survives ad-blockers | Often blocked | Server-side capture |
| Survives cookie consent banner refusal | Partial (Consent Mode) | Yes. No cookies |
| Survives iOS / Safari ITP restrictions | Partial | Yes |
| Captures the source even if visitor browses for a week | Partial | Yes, server-side |
| Privacy & compliance | ||
| Works without cookies | No | Yes |
| Outside ePrivacy / PECR storage-and-access scope | No | Yes |
| Aligned with GDPR, UK GDPR, Australian Privacy Principles | Configurable | By design |
| Setup & cost | ||
| Free tier | Yes | Yes (free tier) |
| Install time | ~10 min + GTM | ~5 min, one tag |
| Need a developer to configure conversions | Often yes | No. Auto-detected |
When you need both
The question isn’t “GA or Lead Source.” It’s “which question am I trying to answer?”
How is traffic to my site trending?. GA. Which marketing channels send the most visitors?. GA. Which pages are bouncing, what’s engaging, what’s slow?. GA.
Which Google Ads campaign produced this $14,000 contract?. Lead Source. How many of last month’s leads actually came from the agency’s SEO work?. Lead Source. If I cut the LinkedIn budget, what would I lose?. Lead Source.
GA is the population-level dashboard. Lead Source is the per-lead receipt. You need both for different decisions.
Things only Lead Source can actually do
Specific capabilities GA literally wasn’t built for. Not opinion. Product limits.
Tell you the name of the person who just converted
GA shows aggregated session data. Lead Source shows you: Dana Okafor, Owner, Okafor & Co, came from Google Ads campaign “Local Services Sydney,” browsed three pages, submitted at 12:43 pm.
Email you when a high-value lead lands
Lead Source sends a real-time notification with the full lead profile attached, before the lead has time to forget they filled out your form. GA has no equivalent.
Write the real source into your CRM contact record
Lead Source pushes the source directly into HubSpot, Salesforce, Close, Keap, Eloqua, or any CRM via webhook. GA has no write-back to your CRM.
Capture leads when cookies are blocked
Lead Source uses no cookies and no client storage. It captures source data server-side at the moment of form submit. GA depends on cookies and degrades sharply when they’re refused or blocked.
Survive a visitor browsing for a week before submitting
GA’s default attribution window is 90 days but cookies are routinely cleared sooner. Lead Source captures the source at the moment of submit using the visitor’s actual session, and the pages they read along the way are there to read back: the full journey to every lead.
Connect spend to customers, not clicks
GA tells you “Google Ads sent 412 sessions.” Lead Source tells you “Google Ads campaign X produced these 7 named leads, of which 2 became customers.” That’s the difference between a vanity metric and a budget decision.
For paid alternatives across the whole category, see the marketing attribution software comparison.