---
agentTools:
  projectIndex: https://developer.zylo.com/llms.txt
---

# August 6, 2026

Custom Fields now support a new `multichoice` type — multi-select fields whose value is an array of selected options — with full support for creation, values, filtering, and one-way conversion from an existing `choice` field.

## Added

### Custom Fields

#### New `multichoice` type

* Custom fields can now be created with `"type": "multichoice"`, Zylo's equivalent of the Multi-Select field type. Like `choice`, it takes an `options` array and an optional `default`; unlike `choice`, its value is an array of selected options rather than a single value.
* A `multichoice` field's value is always returned as an array — an empty array `[]` when unset with no default configured, or a single-element array when a default is configured — never a bare string.
* `custom_fields` values can be updated on Applications, Contracts, and Users (not Payments, where `custom_fields` remains read-only) by passing an array of strings, e.g. `{ "custom_fields": { "regions": ["East", "West"] } }`.
* `multichoice` values can be filtered with `?custom_fields[slug]=option1,option2` (matches records selecting any of the given options) or `?custom_fields[slug]=[option1,option2]` (matches only records selecting all of them).

#### Convert a Choice Custom Field to Multichoice

* An endpoint to convert an existing `choice` custom field to `multichoice` (`POST /v2/customFields/{customFieldId}/convertToMultichoice`). Existing values on the field are migrated automatically — a single selected option becomes a single-element array. This is a one-way conversion: a `multichoice` field cannot be converted back to `choice`.
* MCP and Clarity clients can trigger this conversion with the new `custom_field_convert_to_multichoice` tool, including converting multiple fields at once.

## Changed

### Custom Fields

* Custom field options can no longer be blank/whitespace-only or contain a semicolon (`;`), which is now reserved as the delimiter for multichoice CSV imports. This applies to `choice` and `multichoice` fields.