Pass data with URL parameters
Add parameters to any share link to tag participants with custom fields, pre-fill their details, set their language, and send your own IDs back to your tools.
A share link can carry extra information about whoever clicks it. Add parameters to the end of the link's URL and Strella captures each one as a custom field on that participant. It is a tidy way to record where someone came from, who they are in your own systems, or which campaign sent them.
Parameters connect Strella to your other tools. Tag a link by channel, pass a customer or panelist ID to the interview, and send those same values back out when the participant finishes.
How it works
Take any share link and add parameters to the end. Start with a ?, write each one as name=value, and join additional ones with &:
https://app.strella.io/onboard/your-link-id?source=newsletter&campaign=spring_2026&external_id=12345Every parameter you add becomes a custom field on the participant who clicks it. Each one shows up automatically as its own column in Recruit → Participants, named after the parameter, with no setup required. The example above gives every participant from that link a source of newsletter, a campaign of spring_2026, and an external_id of 12345.
Strella captures the values the moment someone clicks, keeps them through the screener and registration, and saves them on the participant. You can filter, sort, and tag on them like any other column, and they appear on each participant's profile.
Strella ignores case in parameter names, so Source and source
fill the same column. Pick one spelling per field and use it every time.
Reserved parameters
A few names have a built-in meaning. Use them to set the participant's identity and language instead of creating a custom field:
| Parameter | What it does |
|---|---|
first_name, last_name | Set the participant's name and pre-fill (and lock) the name boxes on the registration form. |
email | Sets the participant's email and pre-fills (and locks) the email box on the registration form. |
lang | Sets the language for the screener and interview. Use a language code: es, fr, de, or zh. |
A fully personalized link looks like this:
https://app.strella.io/onboard/your-link-id?first_name=Sam&last_name=Rivera&email=sam@acme.com&lang=esBecause these names are reserved, don't use them for your own tracking. A
parameter called email always fills the email box. It does not create a
separate custom field column.
A few details on lang:
- It only works for supported languages, and the screener and interview must have that language available.
- If a study has language selection turned off, the link's
langis ignored and everyone gets the study's default language. - When
langis absent, participants get the study's default language (English if none is set).
Match the same person across visits
By default, every click creates a new participant. If you're passing an ID you already own (a CRM contact ID, a panelist ID), you can tell Strella to treat that field as the person's identity, so a repeat visit updates the existing participant instead of creating a duplicate.
- Open Manage columns
In Recruit → Participants, open Manage columns and add or edit a text custom field (for example,
external_id). - Turn on “Use as participant identifier”
Turn on the Use as participant identifier toggle. From then on, Strella matches anyone who arrives through a link carrying that field to the existing participant with the same value, instead of adding a new row.
This also stitches together people you've already imported. Upload a CSV with an external_id column, mark that field as the identifier, then send links carrying each person's external_id. Their click attaches to the row you imported instead of duplicating it.
You can't turn on the identifier toggle while duplicate values already exist for that field. Resolve them first: select the duplicates in the table and use Merge Duplicates from the bulk menu, or delete the extras, then enable it.
Send the data back out
Strella can send the values you pass in to your other tools.
- Redirect URLs. When a participant finishes, screens out, hits a full quota, or drops out, Strella appends their custom fields to the redirect URL as parameters. That lets you hand an
external_id(or any other field) back to your panel or downstream tool so both sides stay in sync. Language parameters are not forwarded. - Their call link. Each participant's unique interview link carries their custom fields too, so Copy call link gives you a URL with everything already filled in, ready to paste into an email or message.
Limits & good practice
- One value per parameter. Repeating the same name in a link (
?color=red&color=blue) is ignored. Use a single value per field. - 200 characters max per value.
- Keep it clean. For security, Strella rejects values containing semicolons or script-like content, and the participant cannot enter. Use plain identifiers, names, and labels.
- Parameters are visible in the URL. Don't pass anything secret or sensitive that you wouldn't want the participant (or their browser history) to see.
- Use one link per source. Parameters tag who arrived. Separate share links keep the funnel counts separate for each channel. Use both together.
Related
Manage share links & redirects
Create one or more share links per study. Give each link its own recruitment settings and redirect destinations so different audiences are handled the right way.
Control access & scheduling
Open and close your study. Cap participant counts, schedule a close date, and disqualify off-target answers automatically.