# Link fields and piping

> Pass values like an order number or a name in the survey link, keep them with each response, and show them or earlier answers in your questions.

Source: https://docs.hearsay.co.in/build/link-fields

Link fields (sometimes called hidden fields) carry information you already have, such as an order number, a plan or a customer's name, into the survey through its link. Customers don't type them; they're saved with each response so you can filter by them later.

## Add a link field

1. In the editor, under **Link fields**, choose **Add link field**.
2. Enter the **Name in link**: lowercase, up to 32 characters, such as `order` or `plan`.
3. Optionally add a **Label** (shown in results) and a **Format**: **Any text**, **Email** or **Number**. Values that don't match the format are dropped.
4. Tick **Personal data** for anything that identifies a person, like an email address.

![The Link fields section: names in the link, labels, format and the personal data checkbox](https://firebasestorage.googleapis.com/v0/b/hearsay-53fed.firebasestorage.app/o/docs%2Fshots%2Flink-fields%2Fed3e5287cd777431.webp?alt=media "Link fields")

The names `source`, `ref` and `lang`, and anything starting with `hs_`, are used by Hearsay itself. How many link fields a survey can have depends on the plan: 5 on Free, 20 on Pro, 50 on Business and Enterprise.

## Put values in the link

Add them to the survey link like this:

```text
https://hearsay.co.in/s/SURVEY_ID?plan=pro#email=asha@example.com
```

Put personal data, like email addresses, **after the `#`**. That part of a link isn't sent to servers along the way or kept in their logs. Hearsay reads values from both parts.

To build these links for each customer automatically from Shopify, Klaviyo or Mailchimp, see [Personalised links](https://docs.hearsay.co.in/share/personal-links).

> **Warning: Anyone can edit a link**
>
> Link values are what the link says, not proof of who someone is. Don't use them to decide who gets something valuable.

## Where link values show up

- In each response's details and in CSV and Excel exports, personal fields included.
- In filters, cross-tabs and the **Link fields** chart. Fields marked **Personal data** are left out of these.
- In webhooks, under `response.hidden`.

## Piping

Piping puts an earlier answer or a link value into a question's wording, like "Thanks, Asha! What did you think of your latte?"

1. In the question text, click the `{}` button (**Insert an answer or link field**).
2. Pick an answer under **Answers** or a field under **Link fields**.

Hearsay inserts a token such as `{{hidden:name}}`. Add a fallback for when there's no value: `{{hidden:name|friend}}` shows "friend".

Answers can only be piped from earlier pages, so put the question you pipe from on a page before the one that uses it. Matrix answers can't be piped, and the survey title can't contain tokens.