Arel review
An AST-based SQL builder for Ruby, maintained as part of Rails and Active Record.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Arel is a Ruby library for constructing database queries programmatically. It is aimed at developers working with Rails and Active Record who need query structures represented as an abstract syntax tree (AST), rather than a standalone hosted query-building application. The Rails project says Arel is bundled with the Active Record gem and maintained in the Rails repository. It is open source under the MIT license, making it available without a paid plan.
Its core value is the way it turns query structures into SQL and adapts SQL generation to relational database systems. Query managers cover select, update, and insert operations, while Arel.sql provides an escape hatch for raw SQL literals. This gives Rails developers a way to compose queries structurally while retaining access to literal SQL when needed. The listed capabilities center on SQL construction and compilation; they do not include async queries or type safety, so teams requiring those capabilities should assess another builder.
Arel fits projects already using Ruby and Active Record, where its role as a framework component is an advantage. It is less suited to teams seeking a standalone product, a separate hosted service, or a broad, self-contained feature set. Its supplied feature list is narrower than more comprehensive builders, so buyers prioritizing breadth should compare alternatives. Choose Arel when AST-based query construction and Rails integration are the main requirements; look elsewhere when the project needs a standalone interface or capabilities beyond this focused role.
Arel pros and cons
- Where it wins
- Builds queries from an abstract syntax tree and query structures
- Adapts generated SQL to relational database systems
- Supports select, update, insert, and raw SQL literals
- Where it doesn't
- An internal Rails component rather than a standalone application
- Requires Ruby and the Active Record/Rails ecosystem
- The supplied feature set is narrower than comprehensive query builders
Arel fact sheet, pricing and score →
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