UTM Tracking and Embed Source Attribution in Forms: A Practical Guide

The fastest way to lose attribution on a B2B lead is to ship a form that strips the UTM parameters. The campaign team spends $40,000 driving traffic to a landing page, the form submits, and the CRM record arrives with Lead Source set to "Web" — no campaign, no medium, no source. FlexForm captures the full UTM payload and the embed parent URL on every submission without a tag manager, an extra script, or a hidden-field hack.

This guide walks through how the capture works, how to map UTM data into Salesforce or HubSpot Lead Source, how embed parent URL tracking handles multi-site form rollouts, and where the data shows up across the analytics endpoint and the integration payloads.

What gets captured, automatically

When a respondent opens a FlexForm form, the frontend runs collectSessionMetadata() before the first field renders. The function pulls five values from the URL and one from the parent window, then posts them to the session-create endpoint:

{
  "utm": {
    "source": "google",
    "medium": "cpc",
    "campaign": "summer-launch",
    "term": "form builder",
    "content": "hero-cta"
  },
  "referrer": "https://google.com",
  "pageUrl": "https://flexform.app/f/abc123?utm_source=google&...",
  "embed": {
    "parentUrl": "https://customer-website.com/contact",
    "embedType": "iframe",
    "embedId": "widget-1"
  }
}

The payload lands in form_sessions.metadata at session start and is copied verbatim to form_submissions.metadata on submit. Both columns are JSONB, indexed for the metrics the dashboard uses but free-form enough for downstream queries the dashboard does not surface.

Mapping UTM to CRM Lead Source

UTM in the metadata is only useful if it makes it to the CRM. There are two ways to route the data into Salesforce or HubSpot.

1. 1

   Native integration field mapping

   In the form's HubSpot or Salesforce action, add a mapping from utm.source to the hs_analytics_source / Lead Source field, and utm.campaign to the campaign property. The native integration reads metadata.utm.* directly — no hidden field required. This is the cleanest path and is what we recommend for new forms.

2. 2

   Hidden fields with hideAlways

   If you need the UTM values to appear as form answers (for example, to power conditional logic on submit), add five short_answer elements with hideAlways: true and idSuffix matching the UTM parameter name. FlexForm pre-fills them from the URL automatically, and they land in the submission's values payload alongside the rest of the answers.

Embed parent URL tracking

FlexForm captures the parent page URL when the form is rendered inside an embed. This is the metric almost no competitor exposes, and it answers a question every marketing team eventually asks: which page on our site converts best?

For a single form embedded across a pricing page, a contact page, a blog post, and a partner micro-site, the analytics endpoint returns:

{
  "total": 1248,
  "embedCount": 312,         // 25% of submissions came from an embed
  "byEmbedHost": [           // aggregated from metadata.embed.parentUrl
    { "host": "yoursite.com/pricing",  "count": 142 },
    { "host": "yoursite.com/contact",  "count":  98 },
    { "host": "blog.partner.com/post", "count":  41 },
    { "host": "yoursite.com/blog",     "count":  31 }
  ]
}

That single chart usually retires an entire spreadsheet of A/B-tested embed placements. The pricing page converts 1.5x what the contact page does on the same form — the contact page copy needs the work, not the form. For multi-tenant SaaS where partners embed FlexForm widgets on their own sites, the same data tells you which partners drive volume and which need help with placement. Embed reference covers the configuration.

When UTM and embed source disagree

A common case: the campaign team runs a Google ad pointing at yoursite.com/pricing?utm_source=google&utm_campaign=q2. The pricing page embeds a FlexForm contact form. On submit, the metadata contains both:

• utm.source = google, utm.campaign = q2 (from the URL preserved into the embed)
• embed.parentUrl = yoursite.com/pricing (from the parent window)

The two values describe different things: UTM is where the visitor came from, embed parent URL is where the form was rendered. They are most useful as complementary attribution signals — UTM tells you which campaign earned the click, embed parent URL tells you which page on your site converted it. The analytics dashboard surfaces both in separate breakdowns; the CRM mapping can use either depending on which signal your funnel cares about more.

A worked example: a 30-day attribution audit

A FlexForm design partner ran a 30-day audit on a contact form embedded on five sites. They asked one question: which embed placements drive enough volume to justify the maintenance cost?

The docs embed converted 4 submissions on 290 sessions — 1.4%. The pricing embed converted 142 on 1,840 sessions — 7.7%. The team killed the docs embed (and the form-design effort that went with it), doubled down on the pricing-page copy, and reinvested the time into shipping a partner-specific variant for the partner blog. The decision took about ten minutes once the data was in front of them.

Frequently asked questions