XERJ

XERJ is a search engine for AI agents. Point it at a folder and one command makes your code, docs, logs and PDFs queryable, so an agent asks questions instead of reading files into its context window.

It speaks the Elasticsearch API, so existing clients, dashboards and tooling work against it unchanged.

_{Boot, bulk ingest, search, vector kNN, live dashboards, no cuts. Watch it on xerj.org or try the live playground.}

Install

curl -fsSL https://xerj.org/get | sh

Windows PowerShell:

irm https://xerj.org/get.ps1 | iex

One static binary, no JVM, no dependencies. Prebuilt for Linux, macOS and Windows on x86-64 and arm64. You can also build from source.

Index a folder

Start the server, then point autoindex at anything:

xerj --insecure --data-dir ./data &     # local dev: no TLS, no auth
xerj autoindex ~/my-project

That is the whole setup. There is no schema to write and no pipeline to configure. XERJ sniffs each file, works out what it is, and creates one index per dataset it finds:

phase A: 593 datasets inferred, 1955 junk/skipped files
phase B: indexing 25329 files with 8 workers
done in 158.1s, 593 datasets, 83103 records live, 790 junk records

Source files go through tree-sitter, so code arrives with its symbols and line numbers instead of as flat text. CSV, JSON, JSONL, XML, YAML, SQLite, PDF, DOCX, HTML and common log formats are all handled.

Search it

This is the Elasticsearch API, so you already know this part:

# what did it find?
curl localhost:9200/_cat/indices

# full-text
curl "localhost:9200/ax-*/_search?q=checkout+error"

# structured
curl localhost:9200/ax-orders/_search -H 'content-type: application/json' -d '{
  "query": { "range": { "total": { "gte": 100 } } },
  "aggs":  { "by_status": { "terms": { "field": "status" } } }
}'

Vector and hybrid search use the same knn and semantic syntax you would send to Elasticsearch. Any Elasticsearch client library works if you point it at localhost:9200.

Why it exists

Agents burn their context window reading files. The PHP in WordPress core is about 5.2 million tokens, or 26 full context windows, so an agent cannot simply read it. Grep does not solve this either, because a grep hit is a line and judging that line means opening the whole file.

Querying an index costs kilobytes per question instead. In an AI security audit of WordPress core, an agent worked across 1,492 PHP files on roughly 26,000 tokens, which is what it takes to load about half a percent of the tree.

Use cases

• Code search and security audits: AST-aware indexing, so an agent finds a function instead of a line
• AI search and RAG: full-text, vector and hybrid retrieval in one query, with no separate vector database
• Agent memory: durable recall with a knowledge graph over your own documents
• Log analytics and observability: logs, metrics and traces in one engine
• Elasticsearch replacement: same wire protocol, one binary

Runnable examples live in recipes/ and docs/examples/.

Elasticsearch compatibility

XERJ implements the Elasticsearch REST API: indices, documents, bulk, search, aggregations, mappings, kNN, scroll, reindex and the _cat endpoints. Kibana and the official client libraries connect to it directly.

The conformance suite runs on every commit and currently passes 1360 of 1363 cases. It lives in engine/tests/es-compat-yaml, and the remaining gaps are listed there rather than hidden. XERJ is compatible with the API. It is not a reimplementation of Elasticsearch internals, and it is not a fork.

Benchmarks

XERJ is benchmarked head to head against Elasticsearch 8.13.4 across ingest, full-text search, aggregations, vector search, and reads issued under a concurrent write flood. The latest closed-loop run scores 55 wins, 26 ties, 4 losses, including 1.72x ingest throughput and a 1.61x smaller on-disk footprint.

All four losses are the same gap: read p99 while a high-rate writer runs. It is written up in full rather than left out. Results, methodology and the harness are at xerj.org/benchmarks and in demo/playbooks, so you can rerun them yourself. Treat any number you cannot reproduce with skepticism, including ours.

Build from source

You need a stable Rust toolchain.

git clone https://github.com/xerj-org/xerj
cd xerj/engine
cargo build --release -p xerj-server
./target/release/xerj --insecure --data-dir ./data

To run the conformance suite against a running server:

cargo run --release -p es-yaml-runner -- --dir tests/es-compat-yaml/yaml

Documentation

• Guides and API reference
• Recipes for common tasks
• Roadmap and project layout
• Changelog

Reference pages for individual subsystems, written against the source and including the limits each one does not lift:

• Second brain for the relationship layer over indexed documents: the /_graph routes, evidence on links, the seven detectors and the two-hop cap.
• Scripting for the Painless subset, where scripts run, and the resource limits that bound them.
• Snapshot and restore for the supported subset of the snapshot API, and what restore replaces.
• Security model for authentication, the reserved .xerj-memory-* namespace, API keys and what is not enforced.

Contributing

Pull requests are welcome. See CONTRIBUTING.md for the workflow and CLA.md for the contributor licence agreement, which is one signature per contributor rather than one per pull request.

Bugs and feature requests go to GitHub issues.

License

Apache 2.0.