Arroyo
Arroyo is an open-source distributed stream processing engine for stateful computations on data streams, with sub-second results.
What Arroyo is
Arroyo is an open-source distributed stream processing engine for stateful computations on data streams, with sub-second results. Users define pipelines in analytical SQL, including queries with windows and joins. The engine supports checkpointing for recovery and fault tolerance, exactly-once processing, and horizontal and vertical rescaling. Arroyo says it can handle millions of events per second. Its listed connectors include Kafka, Kinesis, MQTT, NATS, MySQL, Postgres, Redis, Delta Lake, Iceberg, HTTP, WebSocket, and Webhooks. It reads and writes JSON, Avro, Parquet, text, and binary, and includes more than 300 SQL functions; Rust functions can extend SQL. The web UI supports connection management, query development and testing, and pipeline monitoring, while a REST API can manage pipelines. A single-node cluster is for testing and development; production deployments use a distributed cluster with Arroyo’s scheduler or Kubernetes. The engine is Apache 2.0 licensed and self-hostable.
Good
- Supports exactly-once processing and checkpointing
- Includes more than 300 SQL functions
- Provides a web UI and REST API
- Apache 2.0 licensed and self-hostable
Watch out
- Single-node deployment is intended for testing and development
- Production requires a distributed cluster
Who it suits
Arroyo suits teams building stateful stream-processing pipelines with SQL and Rust extensions. A single-node cluster is intended for testing and development; production calls for a distributed deployment.
Verdict
Arroyo combines SQL-based stream processing with checkpointing, connectors, and a web UI. Its deployment guidance distinguishes single-node development from distributed production use.
Plans and prices
From Arroyo's own pricing page, checked 15 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Arroyo open-source | Free | Apache 2.0 engine · self-hosted on Linux/macOS, Docker or Kubernetes |
| Open-source Arroyo Engine | Free | Apache 2.0 licensed; single binary; self-hosted |
| Cloudflare Workers Paid with Pipelines | $5 a month | 50 GB/month SQL transforms · 50 GB/month sink delivery · unlimited stream ingress · $0.04/GB additional SQL · $0.03/GB JSON sink · $0.06/GB Parquet/Iceberg sink · monthly |
The facts
Each one read from Arroyo's own pages, with the date it was checked.
What it does
- Acquisition
- Cloudflare announced on April 10, 2025 that it acquired Arroyo and would integrate its engine into Cloudflare Pipelines, Queues, Workers and R2.checked 15 Oct 2026
- Async UDF limits
- Async Rust UDFs have configurable concurrency and timeout settings; Python UDFs do not support async functions.checked 15 Oct 2026
- Checkpoint storage
- Production deployments can store checkpoints in S3, Google Cloud Storage, Azure Blob Storage or compatible stores such as Minio, R2 and Backblaze B2.checked 15 Oct 2026
- Cloudflare managed limits
- Cloudflare's current Pipelines pricing page lists unlimited stream ingress, 50 GB/month included SQL transforms and 50 GB/month included sink delivery on Workers Paid.checked 15 Oct 2026
- Connectors
- Documented connectors include Kafka, Confluent Cloud, Kinesis, MySQL, Postgres, MQTT, NATS, Redis, Redpanda, Fluvio, Filesystem, Iceberg, WebSocket, SSE, Webhook and HTTP polling.checked 15 Oct 2026
- Data formats
- Native formats include JSON, Avro, Parquet, raw text and raw binary, with custom formats possible through UDFs.checked 15 Oct 2026
- Deployment
- Arroyo can run as a single binary, Docker container or Kubernetes deployment, with SQLite for local use and Postgres recommended for distributed production.checked 15 Oct 2026
- Exactly-once processing
- Arroyo advertises exactly-once processing across out-of-order data and machine failures, using checkpointed state.checked 15 Oct 2026
- Fault tolerance
- The engine supports state checkpointing for fault tolerance and pipeline recovery, and exactly-once processing.checked 4 Oct 2026
- Formats and functions
- Arroyo natively reads and writes JSON, Avro, Parquet, text, and binary, and includes over 300 SQL functions.checked 4 Oct 2026
- Founder and launch
- Y Combinator lists Arroyo as a Winter 2023 company founded in 2022 with founders Micah Wylde and Jackson Newhouse.checked 15 Oct 2026
- GitHub project
- The public repository describes Arroyo as a Rust distributed stream-processing engine and showed about 5.1k stars and 379 forks when opened.checked 15 Oct 2026
- Helm packaging
- Artifact Hub lists an official Arroyo Helm chart for Kubernetes and showed chart/application version 0.15.0.checked 15 Oct 2026
- Joins
- Arroyo SQL supports stream joins including inner, left, right and full joins, plus windowed and updating-data joins.checked 15 Oct 2026
- Kafka integration
- Kafka sources and sinks support self-hosted Kafka, Amazon MSK and Confluent Cloud, with exactly-once or at-least-once sink modes.checked 15 Oct 2026
- Licence
- The official documentation states that Arroyo is fully open source under the Apache 2.0 licence.checked 15 Oct 2026
- Limit: late events
- Events arriving after a watermark has passed are dropped according to the documented watermark semantics.checked 15 Oct 2026
- Limit: operational burden
- The same independent review says self-hosted deployments leave infrastructure responsibility with the customer team.checked 15 Oct 2026
- Limit: state memory
- The concepts documentation says open-source Arroyo stores operator state in worker memory, limiting state size to available worker memory.checked 15 Oct 2026
- Postgres integration
- Postgres connectivity currently uses Debezium through Kafka; the documentation says a native Postgres connector is planned.checked 15 Oct 2026
The company
- Company history
- Arroyo’s founders say they started the company in 2022 and open-sourced the engine in 2023.checked 4 Oct 2026
- Company legal name
- Crunchbase identifies the company legal name as Arroyo Systems, Inc.checked 15 Oct 2026
- Company location and investors
- Crunchbase lists Berkeley, California as headquarters and Y Combinator as the investor in its pre-seed round.checked 15 Oct 2026
- Founded
- 2022checked 28 Sep 2026
Alternatives to Arroyo
- 1
Apache NiFi
Free planOpen sourceWebAPILinuxmacOS7.8Free plan - 2
Apache Beam
Free planOpen sourceWebAPILinuxmacOS7.7Free plan - 3
Esper
Free planOpen sourceAPILinuxmacOSSelf-hosted7.5Free plan - 4
AFL++
Free planAndroidLinuxmacOSSelf-hosted7.2From €20,000 a year - 5
Confluent Cloud
Free planWebAPILinux7.1From $385 a month - 6
Timeplus
Free planWebAPILinuxmacOS7.1From $199 a month