How to send elasticsearch multi search request in Postman?

You can also make your request body be json format and change your Content-Type be application/json, please take a look as below

Three things are important here:

1. When inserting body, select raw radiobutton and Text (or JSON) from dropdown.
2. Add header: Content-type: application/x-ndjson
3. Most important: put new line after the last line of your query

Body:

Header:

Curl version:

curl -X POST \
  http://127.0.0.1:9200/_msearch \
  -H 'cache-control: no-cache' \
  -H 'content-type: application/x-ndjson' \
  -d '{"index":"script","type":"test"}
{"query":{"match_all":{}}}
'