Parse JSON string: from_json

The from_json filter takes a JSON-formatted string and parses it into a Python object (dictionary, list, string, number, or boolean). This is the opposite of to_json, which converts an object into a JSON string.

This is essential when working with data received from external services. Many integrations store JSON data as strings in entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more] states or attributes. For example, MQTT messages, REST sensor responses, and webhook payloads often arrive as JSON strings that you need to parse before you can access individual values. Once parsed, you can use standard dictionary and list operations to extract the data you need. The optional default parameter lets you provide a fallback value if the JSON is invalid, preventing errors in your templatesA template is an automation definition that can include variables for the action or data from the trigger values. This allows automations to generate dynamic actions. [Learn more].

Usage

Here’s how to use this template function. Copy any example and adjust it to your setup.

{{ '{"temperature": 21.5, "humidity": 45}' | from_json }}

{'temperature': 21.5, 'humidity': 45}

Function signature

The signature is a technical summary of this template function. It shows the name of the function, the values (called parameters) it accepts, and what type of data each parameter expects (for example, a piece of text or a number).

Function parameters that have a = with a value after them are optional. If you leave them out, the default value shown is used automatically. Function parameters without a default are required.

value | from_json(
    default: Any = <raises error>,
) -> Any

Function parameters

The following parameters can be provided to this filter.

Using a default value

If the input might not be valid JSON, provide a default to avoid errors.

{{ "not valid json" | from_json(default={}) }}

{}

Good to know

• Without a default, invalid JSON raises an error that can break your template.
• JSON uses double quotes only. Single-quoted strings like '{"a": 1}' need to wrap a string that itself uses double quotes inside.
• Returns the matching Python type: an object becomes a dict, an array becomes a list, null becomes None.

Try it yourself

Ready to test this? Open Developer tools > Template, paste the example into the Template editor, and watch the result update on the right. Edit the values to see how the function adapts to your own entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more].

More examples

Real scenarios where this function comes up in automations and templates. Copy any example and adapt it to your setup.

Parse an MQTT message

Extract a value from a JSON-formatted MQTT sensor payload.

{% set payload = states("sensor.mqtt_sensor") | from_json %}
Temperature: {{ payload.temperature }}
Humidity: {{ payload.humidity }}

Temperature: 21.5
Humidity: 45

Parse a REST sensor response

Access nested data from a REST API response stored as a JSON string.

{% set data = states("sensor.api_response") | from_json %}
{{ data.results | map(attribute="name") | list }}

["Item A", "Item B", "Item C"]

Safe parsing with a default

When processing data that might not always be valid JSON, use a default to keep your templateA template is an automation definition that can include variables for the action or data from the trigger values. This allows automations to generate dynamic actions. [Learn more] working.

{% set data = states("sensor.maybe_json")
   | from_json(default={"status": "unknown"}) %}
Status: {{ data.status }}

Status: unknown

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with your template and expected result, or share on our subreddit /r/homeassistant.

Related template functions

These functions work well alongside this one:

• Serialize to JSON: to_json - Serializes a value to a JSON string.

• Merge dictionaries: combine - Merges multiple dictionaries into one.