Arroyo
activeby Cloudflare (Arroyo Systems) · since 2023 · also known as Arroyo Systems
A Rust stream processor with SQL pipelines, now owned by Cloudflare and powering Cloudflare Pipelines.
Overview
Arroyo is a distributed stream-processing engine written in Rust on Apache Arrow and DataFusion, where pipelines are defined in SQL with windows, joins and UDFs, and state is checkpointed to object storage. It aims to be a lighter, cloud-native alternative to Flink. Cloudflare acquired Arroyo Systems in April 2025 and uses it as the transformation engine of Cloudflare Pipelines, which streams data into R2 and Iceberg tables. The engine remains Apache 2.0 and self-hostable; release cadence has slowed since (0.15.0 in December 2025).
Strengths & trade-offs
Strengths
- +Lightweight Rust engine with fast startup compared with JVM stream processors
- +SQL pipelines with event-time windows and exactly-once checkpoints
- +Backed by Cloudflare and used in production in Cloudflare Pipelines
- +Apache 2.0 licensed
Trade-offs
- −Open-source release cadence slowed after the acquisition
- −Smaller connector ecosystem than Flink
- −Self-hosted docs and community are limited
Great for
- +Streaming ingestion into Iceberg/R2
- +Real-time aggregation of Kafka events
- +Lightweight Flink replacement for SQL pipelines
Think twice for
- −Serving queries directly to applications
- −Teams needing a large, vendor-neutral community
Capabilities
Native or official first-party support · 5 of 25 tracked
Scale & consistency
- Comfortable data size
- Medium · ≤ 10 TB
- Horizontal scaling
- Native
- Multi-region
- No
- Transactions
- None
- Consistency
- Strong
- Schema
- Strict
- Architecture
- Distributed, Single node, Client server
- Query languages
- SQL (DataFusion dialect)
Parallel workers with checkpointed state in S3/R2.
Deployment
available on · Cloudflare
Ecosystem
Alternatives to Arroyo
An Apache-licensed, Postgres-compatible streaming database that stores state on S3 and writes Iceberg.
arroyo vs risingwave →An incremental SQL engine grounded in DBSP theory that updates any SQL query from changes only.
arroyo vs feldera →A Postgres-compatible operational data warehouse that keeps SQL views incrementally up to date.
arroyo vs materialize →A single C++ binary for streaming SQL, built on ClickHouse's engine with streams and windows.
arroyo vs timeplus-proton →Confluent's SQL layer over Kafka Streams, still supported but superseded by Flink SQL for new work.
arroyo vs ksqldb →Streaming lakehouse table format with LSM-based upserts and changelogs, born in Apache Flink.
arroyo vs apache-paimon →Arroyo FAQ
What is Arroyo?
Arroyo is a relational database by Cloudflare (Arroyo Systems), first released in 2023. Arroyo is a distributed stream-processing engine written in Rust on Apache Arrow and DataFusion, where pipelines are defined in SQL with windows, joins and UDFs, and state is checkpointed to object storage. It aims to be a lighter, cloud-native alternative to Flink. Cloudflare acquired Arroyo Systems in April 2025 and uses it as the transformation engine of Cloudflare Pipelines, which streams data into R2 and Iceberg tables. The engine remains Apache 2.0 and self-hostable; release cadence has slowed since (0.15.0 in December 2025).
Is Arroyo open source?
Yes. Arroyo is open source. License: Apache License 2.0.
Does Arroyo support ACID transactions?
No. Arroyo does not provide ACID transactions; its consistency model is strong.
Does Arroyo scale horizontally?
Arroyo scales horizontally out of the box, with built-in sharding or partitioning. It is comfortable at medium scale (≤ 10 TB).
How can I run Arroyo?
You can self-host it, use the vendor's managed cloud and run it serverless. Managed offerings include Cloudflare Pipelines. It is available on Cloudflare.
What is Arroyo best for?
Arroyo is a strong fit for streaming ingestion into Iceberg/R2, real-time aggregation of Kafka events and lightweight Flink replacement for SQL pipelines. Think twice for serving queries directly to applications.
What are the best alternatives to Arroyo?
Common alternatives to Arroyo include RisingWave, Feldera, Materialize, Timeplus Proton and ksqlDB. The right choice depends on your workload, scale and hosting; WhichDB's smart match ranks them against your requirements.
How popular is Arroyo?
Arroyo ranks #385 of 844 databases on the WhichDB Score (5.4/100), and #123 among relational databases. The score combines public adoption signals such as package downloads, GitHub activity, job posts and developer discussion.