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ankane/blazer

A Rails engine for exploring data with SQL, building charts and dashboards, and sharing them with your team.

Open-source alternative to:MetabaseLooker

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What is it?

Blazer is a self-hosted business intelligence dashboard built as a Ruby on Rails engine. Analysts and team members write SQL queries against connected databases, then turn results into tables, charts, and dashboards that others can open and reuse.

It connects to a wide range of data sources, including PostgreSQL, MySQL and MariaDB, Redshift, BigQuery, Snowflake, ClickHouse, Elasticsearch, and SQLite, with a custom adapter option for other stores. Queries can take variables and smart variables that give users dropdowns of labeled values, and chart types are inferred from the column types returned.

Blazer also includes checks that run on a schedule and send email or Slack notifications when data goes bad, plus optional anomaly detection and forecasting through Prophet or Trend. Query permissions, result caching, and audit tracking of queries are included, and access is controlled through your app's existing authentication.

Key features

  • 01Run SQL queries against many databases, including PostgreSQL, MySQL, Redshift, and BigQuery.
  • 02Automatically generate line, column, scatter, pie, and map charts from query results.
  • 03Build dashboards from multiple queries, with shared variables.
  • 04Schedule data checks that notify by email or Slack when results fail.
  • 05Cache query results and track all queries for auditing.
  • 06Create database tables from CSV uploads (PostgreSQL).

Use cases

  • Giving a product or operations team self-serve SQL access to company data inside an internal Rails app.
  • Monitoring data quality with scheduled checks that alert when bad rows appear.
  • Sharing recurring metrics as dashboards that stakeholders can filter with variables.
  • Running cohort analysis from simple SQL queries against an existing database.

Quick start

  1. 1

    Add the gem to your Rails app's Gemfile

  2. 2

    Run the install generator

    rails generate blazer:install
  3. 3

    Run database migrations

    rails db:migrate
  4. 4

    Mount the engine in config/routes.rb

Things to know

  • It is a Rails engine, so it only works inside a Rails application.
  • Production use requires you to set up authentication yourself.
  • Protecting against data changes relies on a read-only database user that you must create.

Topics

#sql#business-intelligence#dashboard#charts#ruby-on-rails#data-visualization

FAQ

What is blazer?
A Rails engine for exploring data with SQL, building charts and dashboards, and sharing them with your team. Blazer is a self-hosted business intelligence dashboard built as a Ruby on Rails engine. Analysts and team members write SQL queries against connected databases, then turn results into tables, charts, and dashboards that others can open and reuse.
Is blazer free to use? What license does it have?
blazer is open source under the MIT license. Check the license terms before using it in commercial products.
Is blazer still maintained?
Actively maintained. The last commit to blazer was on Oct 20, 2026.
What can I use blazer for?
Giving a product or operations team self-serve SQL access to company data inside an internal Rails app. Monitoring data quality with scheduled checks that alert when bad rows appear. Sharing recurring metrics as dashboards that stakeholders can filter with variables. Running cohort analysis from simple SQL queries against an existing database.
How do I install blazer?
Add the gem to your Rails app's Gemfile Run the install generator: rails generate blazer:install Run database migrations: rails db:migrate Mount the engine in config/routes.rb
Where can I get blazer?
The source code and installation instructions are on GitHub: https://github.com/ankane/blazer

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