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Arroyo

arroyo.dev

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Spec score 9.2 #1 of 26 in Stream Analytics Software

What it is

Arroyo is an open-source distributed engine for processing stateful computations on data streams, with sub-second results. Users build streaming pipelines in analytical SQL, including complex queries, windows and joins. Arroyo supports checkpointing for fault tolerance and recovery, exactly-once processing, and horizontal and vertical rescaling; it says the engine can handle millions of events per second. Its connectors include Kafka, Kinesis, MQTT, MySQL, Postgres, Redis, Delta Lake, HTTP and WebSocket, among others. It reads and writes JSON, Avro, Parquet, text and binary, and includes more than 300 SQL functions. Rust scalar, aggregate and asynchronous user-defined functions can extend SQL. The web UI supports connection management, query development and testing, and pipeline monitoring; pipeline management is also available through a REST API. Single-node clusters are intended for development and testing, while production deployments use a distributed cluster with Arroyo’s scheduler or Kubernetes. It is Apache 2.0 licensed, free at free, and self-hostable.

Spec sheet

What it does
Arroyo is a Rust distributed stream-processing engine for running SQL over bounded and unbounded event streams with sub-second results.Read 15 Oct 2026 · doc.arroyo.dev
Purpose
Arroyo is a distributed stream processing engine for stateful computations on data streams, with sub-second results.Read 4 Oct 2026 · doc.arroyo.dev
Deployment
Arroyo can run as a single binary, Docker container or Kubernetes deployment, with SQLite for local use and Postgres recommended for distributed production.Read 15 Oct 2026 · doc.arroyo.dev
Support
The deployment guide invites users rolling out clusters to contact [email protected] or ask questions on Discord.Read 4 Oct 2026 · doc.arroyo.dev
Founded
2022Read 28 Sep 2026 · arroyo.dev
Acquisition
Cloudflare announced on April 10, 2025 that it acquired Arroyo and would integrate its engine into Cloudflare Pipelines, Queues, Workers and R2.Read 15 Oct 2026 · blog.cloudflare.com
Async UDF limits
Async Rust UDFs have configurable concurrency and timeout settings; Python UDFs do not support async functions.Read 15 Oct 2026 · doc.arroyo.dev
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.Read 15 Oct 2026 · doc.arroyo.dev
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.Read 15 Oct 2026 · developers.cloudflare.com
Company history
Arroyo’s founders say they started the company in 2022 and open-sourced the engine in 2023.Read 4 Oct 2026 · arroyo.dev
Company legal name
Crunchbase identifies the company legal name as Arroyo Systems, Inc.Read 15 Oct 2026 · crunchbase.com
Company location and investors
Crunchbase lists Berkeley, California as headquarters and Y Combinator as the investor in its pre-seed round.Read 15 Oct 2026 · crunchbase.com
Connectors
Documented connectors include Kafka, Confluent Cloud, Kinesis, MySQL, Postgres, MQTT, NATS, Redis, Redpanda, Fluvio, Filesystem, Iceberg, WebSocket, SSE, Webhook and HTTP polling.Read 15 Oct 2026 · doc.arroyo.dev
Data formats
Native formats include JSON, Avro, Parquet, raw text and raw binary, with custom formats possible through UDFs.Read 15 Oct 2026 · arroyo.dev
Exactly-once processing
Arroyo advertises exactly-once processing across out-of-order data and machine failures, using checkpointed state.Read 15 Oct 2026 · arroyo.dev
Fault tolerance
The engine supports state checkpointing for fault tolerance and pipeline recovery, and exactly-once processing.Read 4 Oct 2026 · doc.arroyo.dev
Formats and functions
Arroyo natively reads and writes JSON, Avro, Parquet, text, and binary, and includes over 300 SQL functions.Read 4 Oct 2026 · arroyo.dev
Founder and launch
Y Combinator lists Arroyo as a Winter 2023 company founded in 2022 with founders Micah Wylde and Jackson Newhouse.Read 15 Oct 2026 · ycombinator.com
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.Read 15 Oct 2026 · github.com
Helm packaging
Artifact Hub lists an official Arroyo Helm chart for Kubernetes and showed chart/application version 0.15.0.Read 15 Oct 2026 · artifacthub.io
Joins
Arroyo SQL supports stream joins including inner, left, right and full joins, plus windowed and updating-data joins.Read 15 Oct 2026 · arroyo.dev
Kafka integration
Kafka sources and sinks support self-hosted Kafka, Amazon MSK and Confluent Cloud, with exactly-once or at-least-once sink modes.Read 15 Oct 2026 · doc.arroyo.dev
Licence
The official documentation states that Arroyo is fully open source under the Apache 2.0 licence.Read 15 Oct 2026 · doc.arroyo.dev
Limit: late events
Events arriving after a watermark has passed are dropped according to the documented watermark semantics.Read 15 Oct 2026 · doc.arroyo.dev
Limit: operational burden
The same independent review says self-hosted deployments leave infrastructure responsibility with the customer team.Read 15 Oct 2026 · cloudimg.co.uk
Limit: state memory
The concepts documentation says open-source Arroyo stores operator state in worker memory, limiting state size to available worker memory.Read 15 Oct 2026 · doc.arroyo.dev
Postgres integration
Postgres connectivity currently uses Debezium through Kafka; the documentation says a native Postgres connector is planned.Read 15 Oct 2026 · doc.arroyo.dev
Praise: usability
An independent Arroyo review highlights SQL pipelines, windows, joins, aggregations and event-time processing as key strengths.Read 15 Oct 2026 · cloudimg.co.uk
Production limitation
The deployment guide states that a single-node cluster is suitable for testing and development but not production.Read 15 Oct 2026 · doc.arroyo.dev
Python requirement
Python UDF execution requires Python 3.12 or later, and additional Python packages must be installed manually.Read 15 Oct 2026 · doc.arroyo.dev
Release news
Arroyo 0.15.0 was released December 1, 2025 with a complete Iceberg sink and other fixes and improvements.Read 15 Oct 2026 · arroyo.dev
REST API
The public REST API can create, operate and manage pipelines, connections and related resources.Read 15 Oct 2026 · doc.arroyo.dev
Scale
Arroyo says it can scale to millions of events per second and supports horizontal and vertical rescaling.Read 4 Oct 2026 · arroyo.dev
Security configuration
The Kubernetes deployment guide describes AWS IAM Roles for Service Accounts as the most secure way it covers to grant pods access to AWS resources.Read 4 Oct 2026 · doc.arroyo.dev
SQL functions
The product website says Arroyo includes more than 300 window, aggregate and scalar SQL functions.Read 15 Oct 2026 · arroyo.dev
SQL pipelines
Pipelines are authored in SQL using an Apache DataFusion-based dialect extended with streaming windows, watermarks and event-time joins.Read 15 Oct 2026 · doc.arroyo.dev
Supported storage
Checkpoint and artifact storage options include S3-compatible stores, R2, GCS, Azure Blob Storage, and local filesystems.Read 4 Oct 2026 · doc.arroyo.dev
System requirements
The getting-started documentation says Linux and macOS are well supported locally; release binaries are provided for Linux x86/ARM and macOS M1.Read 15 Oct 2026 · doc.arroyo.dev
Telemetry
Arroyo collects limited anonymous usage telemetry by default and allows opt-out with DISABLE_TELEMETRY=true.Read 15 Oct 2026 · doc.arroyo.dev
Time windows
The engine supports tumbling, sliding and session windows with watermark-aware processing.Read 15 Oct 2026 · doc.arroyo.dev
UDF extensibility
Users can add scalar UDFs in Rust or Python, while aggregate UDFs and asynchronous UDFs are currently Rust-only.Read 15 Oct 2026 · doc.arroyo.dev
User-defined functions
Users can extend SQL with Rust scalar, aggregate, and asynchronous user-defined functions.Read 4 Oct 2026 · arroyo.dev
Web UI
The Web UI is used to manage connections, develop and test SQL, create UDFs and monitor pipelines.Read 15 Oct 2026 · arroyo.dev
Web UI and API
The Web UI supports managing connections, developing and testing SQL queries, and monitoring pipelines; pipelines can also be managed through a REST API.Read 4 Oct 2026 · arroyo.dev

Plans and prices

Arroyo open-source Free Apache 2.0 engine · self-hosted on Linux/macOS, Docker or Kubernetes Read 15 Oct 2026 · doc.arroyo.dev
Open-source Arroyo Engine Free Apache 2.0 licensed; single binary; self-hosted Read 4 Oct 2026 · arroyo.dev
Cloudflare Workers Paid with Pipelines $5 a month monthly 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 Read 15 Oct 2026 · blog.cloudflare.com

Every Arroyo plan and price →

Strong points and limits

Strong points

  • Apache 2.0 licensed and self-hostable
  • Supports exactly-once processing
  • Includes more than 300 SQL functions
  • Provides a web UI and REST API
  • Supports multiple checkpoint storage options

Limits

  • Single-node clusters are intended for testing and development
  • Production requires a distributed cluster
  • Kubernetes AWS access guidance covers IAM roles for service accounts

Who it suits

Arroyo suits teams building stateful streaming pipelines with SQL and those needing Rust extensions. Its single-node setup is intended for testing and development; production deployments use a distributed cluster.

Verdict

Arroyo offers SQL-based stream processing with checkpointing, connectors and Rust extensions. The free open-source engine can run self-hosted, but production calls for a distributed deployment.

Where Specifiction places it

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