Decode text and image payloads

Read encoded text in the received-message panel without changing the broker’s message.

About 2 minutes · MQTT Viewer 1.2 · Web UI screenshots

Before you start

Receive a topic carrying Base64 or hexadecimal text. For example, SGVsbG8gTVFUVA== is Base64 for Hello MQTT.

1. Decode Base64 text

Select the topic, open Payload, then choose Base64 from Decode. The example contains a JSON temperature reading.

Base64 decoding reveals the JSON text inside the received payload.
Base64 decoding reveals the JSON text inside the received payload. Full size (opens in a new tab)

2. Decode hexadecimal text

For a hex-encoded topic, open the decoding menu and choose Hex. The menu shows Decode or the current encoding. The text 48656c6c6f204d515454 becomes Hello MQTT. Choose No decoding to return to the original text.

Hex decoding changes the displayed representation, not the stored broker message.
Hex decoding changes the displayed representation, not the stored broker message. Full size (opens in a new tab)

3. View an image payload

Select a topic carrying PNG, JPEG, GIF, WebP or BMP bytes. The payload panel detects the image and shows a preview. Click View raw bytes below it to inspect the underlying message.

An MQTT message containing a PNG appears as an image preview.
Publish the image bytes directly to use the image preview. Full size (opens in a new tab)

Choose the encoding that was actually used

Base64 and Hex are encodings, not schema-based decoders. Use the Sparkplug guide for Sparkplug traffic. The publish editor’s Encode control is a separate operation applied when sending.