The Write to field, Increase/decrease field and Clear field actions — built-in and custom fields, the number rule, placeholders and the rules a field change triggers.
You need somewhere to keep the customer's city, their order number, their appointment date or how many times they entered the wrong code. Field actions write that information to the contact card, count it and clear it when the time comes. This article covers three actions one by one: , and .
Write to field
Increase/decrease field
Clear field
💡 What a field is and how it differs from a tag is covered in Contact field (custom field). This article deals with the behaviour of the actions.
In this article you will find:
Choosing a field: built-in or custom
Write to field
Increase/decrease field
Clear field
A field change triggers global rules
A concrete example: brute-force protection
Limits and known issues
Common mistakes
Choosing a field: built-in or custom
The first box of all three actions is the field picker, and it offers two options.
Built-in fields — Name, Email, Phone. These are the contact card's own columns; they appear in the same place everywhere in the panel.
Custom field — A field you define yourself. When you choose it, a text box opens next to it for the field's key.
A custom field key is made of lowercase letters, digits and underscores, starts with a letter and is at most 40 characters long: city, cart_total, appointment_date, attempts. If you type capitals or accented letters, the panel corrects them for you; if an invalid key remains, the box is marked as invalid and the pre-publish check raises "An action is incomplete".
You do not have to define a field anywhere else: it comes into existence the first time it is written.
Write to field
The Write to field action puts a value into a field. If the field already holds something, it is overwritten.
Choose Write to field as the kind.
Pick a built-in field or Custom field in the field picker.
Type the value into the Value box (at most 500 characters).
The value box processes placeholders. The key you pick from the placeholder menu below the box is inserted at the cursor. The most common pattern is this: to carry the person's answer into a field, write {{input}} as the value.
Other useful keys: {{contact.first_name}}, {{contact.email}}, {{contact.phone}}, {{workspace.name}} and, for another field's value, {{field.field_name}}. An unrecognised key is left empty and the pre-publish check raises a warning.
Leading and trailing spaces are dropped as the value is written. Writing an empty value clears the field — in that case using the Clear field action instead makes your intent clearer.
Increase/decrease field
The Increase/decrease field action changes the number in a field. That is how you keep counters, scores and quantities.
Choose Increase/decrease field as the kind.
Pick the field. Use a custom field for this action.
Type the number into the Amount box. A positive value increases; a negative value decreases.
The number rule is this: if the value in the field cannot be read as a number, it counts as 0. The practical consequence is a pleasant one — the first increase on an empty field results in 1, and you never have to zero the field first. A field holding "three" also counts as 0, so the result of an increase is 1.
Both a dot and a comma are accepted as the decimal separator, so adding 1 to a field holding "2,5" gives 3,5.
⚠️ Note: Do not use this action on the Name, Email and Phone fields. Those fields are not numbers; increasing them replaces their contents with a number and you lose the person's phone or name. Counters always live in a custom field.
Clear field
The Clear field action empties a field and has no other setting.
Choose Clear field as the kind.
Pick the field to clear.
A cleared custom field disappears from the contact card entirely; a cleared built-in field is left empty. A cleared field is caught by the is empty operator in conditions.
The action is useful in two places: resetting temporary counters at the end of a flow, and answering a customer's "delete my information" request inside a flow.
A field change triggers global rules
All three actions have a side effect worth knowing: when a field changes, global rules are notified.
If a rule under Automations › Rules is bound to the Field changed event, the value your flow writes runs that rule. The rule's Field (filter) box lets it listen to one specific field only.
The same information also appears in the panel straight away: the moment the field is written, the contact card in the inbox and the Contacts screen refresh; you do not need to reload the page.
This applies not only when you fill the field with Write to field, but also with the Collect information, External request and AI steps: they all feed the same rule chain.
A concrete example: brute-force protection
A courier company verifies the order code before asking for a tracking number, and limits wrong attempts:
Message: "Type your order code." (Wait for reply on)
True branch → Action:Clear field (attempts), then the tracking information is sent.
False branch → Action:Increase/decrease field (attempts, +1).
Condition: "Field · attempts · greater than · 2"
True branch → Action:Notify the team ("Three wrong codes") and Hand over to a person.
False branch → back to the second step, and the code is asked again.
Three actions together build a flow that is both safe and polite: the customer gets three attempts and is then connected to a human.
Limits and known issues
A Write to field value is at most 500 characters.
A custom field key is at most 40 characters, starts with a letter and contains only lowercase letters, digits and underscores.
The amount of an increase is between -1,000,000 and 1,000,000.
A value that cannot be read as a number counts as 0.
A placeholder is only filled in the value box of Write to field. Increase/decrease field and Clear field take none.
Field values are stored as text. If you plan to compare numerically in a condition, write only digits into the field and keep currencies and units in the message.
The three actions are separate plan features; if your plan does not cover one, the session stops at that step.
An invalid field key blocks publishing.
Common mistakes
Trying to build a counter with Write to field. "Write to field" changes the value, it does not count. Counting needs Increase/decrease field.
Writing a unit into a numeric field. "750 USD" is not a number; the greater than rule in a condition returns the wrong result.
Increasing a built-in field. Name, email and phone are not numbers; counters live in custom fields.
Writing fixed text instead of {{input}}. To save the person's answer, the value must hold a placeholder.
Overwriting a field without checking whether it is filled. Put a "Field · is empty" condition in front of it so you do not lose information the customer gave earlier.
Forgetting to clear temporary counters. Empty the counter fields you no longer need with Clear field when the flow ends.