Tracking which marketing campaigns actually work shouldn’t be a black box. If you’re running ads, email blasts, or social posts, you want to know which ones drive real leads—not just guess and hope. This guide is for marketers, ops folks, or anyone using HubSpot Forms who’s tired of seeing “Unknown Source” or “Direct Traffic” in their reports.
Hidden fields give you a way to quietly capture campaign details behind the scenes so you can tie every form submission back to the right ad or email. Here’s how to set them up, what to watch out for, and what’s honestly worth your time.
Why Hidden Fields Matter (and Where They Fall Short)
Hidden fields are extra form fields that visitors never see, but that capture information in the background—like campaign name, UTM parameters, or the page someone landed on. They’re essential if you want to:
- Link new leads to the exact campaign or ad they came from
- See which channels are actually converting (not just driving traffic)
- Automate lead segmentation in your CRM
But let’s be clear: hidden fields aren’t magic. They can’t fix bad tracking, and they won’t backfill missing data. If someone bounces from a landing page or blocks cookies, you may still get blanks. Still, for most marketing teams, they’re the fastest way to connect forms to campaigns without a pile of custom code.
Step 1: Decide What You Want to Track
Before you start adding hidden fields everywhere, be specific about what you want to learn. Otherwise, you'll end up with a bunch of fields no one ever uses.
What’s actually useful:
- UTM parameters (utm_source, utm_medium, utm_campaign, etc.)
- Referrer URL (where the visitor came from)
- Landing page (the page where the form lives)
- Lead source (if you’re passing this from ads or emails)
What’s usually noise:
- Gimmicky stuff like “form version” or “widget color”—stick to things you’ll actually report on.
Pro tip:
If you’re running paid campaigns, start with the UTM parameters. They’re the industry standard for a reason.
Step 2: Set Up Your Hidden Fields in HubSpot Forms
Let’s get practical. Here’s how to add hidden fields to a form in HubSpot:
- Create or Edit Your Form
- Go to your HubSpot dashboard.
- Under “Marketing” > “Lead Capture,” click “Forms.”
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Choose an existing form or hit “Create form.”
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Add a Hidden Field
- In the form editor, drag in the field you want (e.g., “Campaign Source”).
- Click on the field, then check the “Make this field hidden” box in the options.
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If you don’t have a property for this yet, you’ll need to create it—use clear names like “utm_campaign” so it’s obvious what’s being captured.
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Map Hidden Fields to CRM Properties
- Make sure each hidden field points to a property in your CRM. Otherwise, you’ll collect data that never gets used.
A word of warning: Don’t go overboard. Every field you add is another potential headache for your CRM and reporting later.
Step 3: Autofill Hidden Fields with URL Parameters
A hidden field isn’t much use unless it actually grabs the right info. The most common way is to use URL parameters (like ?utm_source=facebook&utm_campaign=spring_sale) from your ads or emails.
How it works in HubSpot:
- By default, if a hidden field’s name matches a URL parameter, HubSpot will autofill that field when someone lands on the page.
- For example, if your form has a hidden field called “utm_campaign” and the page URL is
.../landing-page?utm_campaign=spring_launch, HubSpot plugs “spring_launch” into that field automatically.
What to watch out for: - Field names must match the parameter names exactly (case-sensitive). - If you’re using a CMS or builder that strips URL parameters, you’ll lose this data—test your landing pages! - People who land on the page without UTM parameters (e.g., from bookmarks, organic search) won’t fill these fields. That’s normal.
Pro tip:
Always test your links and forms before going live. Paste your full ad URL with UTMs, submit the form, and check the lead’s record to see if the data shows up.
Step 4: Pass Hidden Field Data to Your CRM (and Use It)
Collecting campaign data is only half the battle. You need a plan for what happens next.
- Sync fields to your CRM: Make sure your hidden fields update the right properties on the contact record.
- Set up reports or lists: Use these properties to filter contacts by campaign, source, or medium. This is how you’ll actually see what’s working.
- Automate follow-ups: If certain campaigns create hot leads, use workflows to route them to sales or trigger custom emails.
Things that trip people up: - Data overwrites: If a contact fills out multiple forms, HubSpot may overwrite the old value with the new one. You might lose the “first touch.” If first-source is critical, use dedicated “original source” fields. - Dirty data: Typos in UTM tags or inconsistent naming (“Facebook” vs. “facebook”) will make reporting a headache. Standardize your tags and teach your team to use them consistently.
Step 5: Keep It Clean—Audit and Improve
Hidden fields are “set and forget” until they break or get messy. A little maintenance goes a long way.
- Review your forms quarterly: Are you still tracking the right things? Any fields collecting dust?
- Spot-check data in your CRM: Look for blanks or weird values. If a campaign’s data isn’t coming through, double-check the form and URLs.
- Kill zombie fields: Old hidden fields you’re not using anymore? Remove them. Less clutter means less confusion.
What not to stress about: - Don’t chase 100% attribution. Some leads will always slip through without campaign data. Focus on trends and what’s working overall.
What Works, What Doesn’t, and What to Ignore
What works: - Using hidden fields for UTM tracking—simple, reliable, and integrates with standard reporting. - Automating follow-ups based on campaign source—helpful for sales.
What doesn’t: - Relying on hidden fields alone if you need multi-touch attribution or deep analytics. That’s a different (and more complicated) beast. - Trying to track every little detail “just in case.” Too many fields = messy data.
Ignore the hype about: - Fancy scripts or complex tracking setups unless you really need them. For most teams, basic hidden fields and clean UTM tags get the job done.
Keep It Simple, Fix What Matters
You don’t need to reinvent the wheel. Hidden fields in HubSpot Forms are a solid, low-maintenance way to track which campaigns are pulling their weight. Start with the basics—UTMs and lead source—test your setup, and check your CRM to make sure data’s flowing. If you keep things simple and tune up your forms every few months, you’ll get the insight you need without creating a data monster.
Now go see which campaigns are actually earning their keep.