Free tool

Index template and mapping generator

Paste one real document. Every field gets a suggested Elasticsearch type and the reason for it; change any of them, set shards, index mode and ILM, then copy the component templates, index template and a test sequence for Dev Tools.

Runs entirely in your browser. Nothing you enter is sent anywhere.

1. Sample document

One JSON document, or NDJSON (the first non-empty line is used) Paste a real document as it will reach Elasticsearch (after any ingest pipeline). Ctrl+Enter reads it. It never leaves this page.

2. Fields and types

Every field of the document, nested objects and arrays of objects included, with a suggested Elasticsearch type and the reason. Change any type from its menu; options appear for the type you pick. Only parameters accepted by both 8.19 and 9.5 are offered (checked against both with _simulate).

Field	Sample	Type and options	Why

3. Template

Template nameAlso names the component templates (name-settings, name-mappings) and the ILM policy. Index patternsComma separated. Lower case only. PriorityBuilt-in logs-*-*, metrics-*-*, synthetics-*-* use 100; Fleet integrations up to 200. Elastic: with Fleet or Elastic Agent stay below 100; to take over a built-in pattern deliberately go above 500. Elasticsearch majorChanges the notes on index modes and the built-in templates checked. The requests are the same on both.

Data stream (append-only, @timestamp required, rolls over to new backing indices)

Settings

Primary shardsElasticsearch default 1. Blank leaves it out. ReplicasElasticsearch default 1. Blank leaves it out. refresh_intervalBlank = default 1s (search-idle shards skip it). 30s cuts indexing cost. total_fields.limitindex.mapping.total_fields.limit. Blank = default 1000. dynamic index.mode

index.codec: best_compression (smaller stored fields, some CPU on merge and fetch)

4. Lifecycle (ILM)

ILM policy

Existing policy nameSets index.lifecycle.name. Check it exists with GET _ilm/policy/<name>.

Hot: max_primary_shard_sizeRoll over when a primary shard reaches this. 50gb is the size Elastic uses in its default policies. Hot: max_ageOr when the index is this old (30d in Elastic's default policies). Whichever comes first. Warm after (days)Blank skips the phase. Counted from rollover. Cold after (days) Delete after (days)

Force merge to 1 segment in warm

Warm and cold set an index priority (50, 0) for recovery order; ILM moves indices to warm and cold data tiers on its own when those nodes exist.

Rollover alias (plain index only)A plain index rolls over through a write alias. Blank with "create" uses the template name. The test tab bootstraps <alias>-000001.

Test

Test index or data stream nameBlank = the first index pattern with * replaced by "test" (or <alias>-000001 for a rollover index).

5. Checks

-mapped fields (objects and multi-fields count)

1000total fields limit

0problems Elasticsearch rejects

0warnings

6. Requests for Kibana Dev Tools

Every request here was applied to Elasticsearch 8.19.23 and 9.5.5 in our tests: component templates, ILM policy, index template, _simulate_index, the sample document and the mapping read back field by field. A template that is right can still sit on a cluster that is not: Run the full diagnostic.

Read with this tool

Elasticsearch Index Templates, Component Templates, Data StreamsHow composable templates merge, how priority resolves conflicts, how data stream backing indices roll over, and when a plain index is the better choice.Elasticsearch Mapping Design for Production: Types and LimitsDesign Elasticsearch mappings that stay fast and small: text vs keyword, doc_values, index: false, dynamic templates, strict mode, flattened and field limits.Elasticsearch ILM Troubleshooting: Fixing Stuck PoliciesRead _ilm/explain like a state machine, fix rollover alias and allocation errors, retry or move a stuck step, and change a policy on indices already in flight.Cutting Elasticsearch Storage Costs: logsdb, TSDS and CodecsMeasure where Elasticsearch disk goes per field, then cut it with logsdb, TSDS, synthetic _source, best_compression, mapping trims, force merge and frozen.