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brettwooldridge/hikaricp

★ 21,106JavaAudience · developerComplexity · 2/5QuietLicenseSetup · easy

TLDR

A lightweight, high-performance Java library that manages a pool of reusable database connections, eliminating the overhead of opening and closing connections repeatedly.

Mindmap

mindmap
  root((HikariCP))
    What it does
      Manages DB connections
      Reuses connections
      Reduces overhead
    Key features
      Zero overhead design
      Sensible defaults
      Lightweight 90KB
    Configuration
      Database URL
      Username password
      Pool size settings
      Timeout options
    Tech stack
      Java 7 and 8
      JDBC
      Maven Central
    Use cases
      Web applications
      High-traffic systems
      Production deployments

Things people build with this

USE CASE 1

Speed up web applications by reusing database connections instead of creating new ones for each query.

USE CASE 2

Build high-traffic systems that need to handle many concurrent database requests without connection overhead.

USE CASE 3

Replace slower connection pool libraries like commons-dbcp2 or c3p0 in existing Java projects.

Tech stack

JavaJDBC

Getting it running

Difficulty · easy Time to first run · 5min
Use freely for any purpose, including commercial use, as long as you keep the copyright notice.

In plain English

HikariCP is a JDBC connection pool for Java applications. A connection pool is a behind-the-scenes pool of pre-opened database connections that an application can borrow and return, instead of opening a fresh connection every time it needs to talk to the database. Opening connections is slow, so reusing them makes the app faster and steadier under load. The README calls itself "zero-overhead" and emphasises that the whole library is small, around ninety kilobytes, and that simplicity is the main reliability feature. You configure it with a handful of properties. The "essentials" are either a dataSourceClassName (the JDBC driver's data-source class) or a jdbcUrl (an older connection-URL style), plus a username and password. From there, the most commonly tuned knobs are autoCommit (whether each operation is automatically saved), connectionTimeout (how long the app will wait for a free connection before giving up, thirty seconds by default), and idleTimeout (how long an unused connection is allowed to sit before being closed). All time values are in milliseconds, and the README stresses that the defaults are deliberately sane, so most projects need almost no tweaking. Someone would use HikariCP when building a Java service that talks to a relational database and wants fast, dependable connection handling without writing it themselves. It is published as a Maven artifact under the group com.zaxxer, with the main artifact targeting Java 7 and Java 8 and a separate artifact for Java 6 kept in maintenance mode. The README also points to JMH micro-benchmarks comparing it to other pools, and notes that the full README is longer than what was provided.

Copy-paste prompts

Prompt 1
Show me how to set up HikariCP in a Spring Boot application with just a database URL, username, and password.
Prompt 2
How do I configure HikariCP's maximum pool size and connection timeout for a high-traffic web service?
Prompt 3
What are the key performance differences between HikariCP and other Java connection pools like c3p0?
Prompt 4
Help me integrate HikariCP into my existing Java application to reduce database connection overhead.
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Generated 2026-05-21 · Model: sonnet-4-6 · Verify against the repo before relying on details.