RRDtool

Free plan APILinuxSelf-hostedWindows

What RRDtool is

RRDtool is an open-source system for logging and graphing time series data. It creates Round Robin Database files from configured data sources and archives, each of which retains a configured number of values as older entries cycle out. Built-in consolidation functions include AVERAGE, MIN, MAX, and LAST; specialized archives support Holt-Winters smoothing, confidence bands, and detection of aberrant behavior. Data can be supplied through command-line use, standard-input pipes, or applications and scripts using Perl, Python, Ruby, Lua, and Tcl. The distribution includes bindings for Perl, Tcl, Ruby, and Python, while its download page also lists PHP and Node.js bindings. RRDtool can export data from one or more database files in XML, and its documentation describes rrdcached as a caching daemon. It is distributed as source, with binary distributions listed for several systems. RRDtool is free under GNU GPL V2 or later. Its documentation cautions that pre-filling an RRD does not guarantee data correctness.

Who it suits

RRDtool suits developers and operators who need to log and graph time series data using configured retention and consolidation. Its source distribution and programming interfaces fit users comfortable with a self-managed, code-oriented tool.

What it does well

Free and open source under GNU GPL V2 or later
Archives cycle older values out as configured
Includes classic consolidation and forecasting functions
Supports command-line, pipe, and language-based ingestion

What to know first

Pre-filled RRD data is not guaranteed correct
The maker says modified versions cannot use a different license

Limits

Round Robin Archives retain a configured number of values, with older values cycling out as the archive is updated. The maker’s documentation says pre-filling an RRD is a best effort and does not guarantee data correctness.

Plans

Plan	Billed and limits	Price
RRDtool	Open source; GNU GPL V2 or later	Free

As oss.oetiker.ch lists them, read 11 Oct 2026. The maker's own page has the final word.

Getting started

Visit oss.oetiker.ch/rrdtool.
Obtain the source distribution or a listed binary distribution for a supported system.
Configure data sources and archives for an RRD file.
Supply data through the command line, standard-input pipes, or a supported language interface.
Use RRDtool to graph or export data as needed.

Verdict

RRDtool offers configurable time-series storage, graphing, and data-processing options at no listed cost. Consider its GPL licensing and the documented limitation on pre-filled data when deciding whether it fits your use.

Questions

Does RRDtool cost anything?

RRDtool has a free plan and is available as open-source software under GNU GPL V2 or later.

Which platforms are listed?

The listed platforms include API, Linux, self-hosted, and Windows. Binary distributions are also listed for Debian Linux, Solaris, HP-UX, and Cygwin Windows.

Which programming languages can use RRDtool?

It can be integrated with Perl, Python, Ruby, Lua, or Tcl applications. The distribution includes Perl, Tcl, Ruby, and Python bindings; the download page also lists PHP and Node.js bindings.

What data-retention behavior does it use?

Round Robin Archives store a configured number of values. Older values cycle out as the archive is updated.

Can RRDtool be sold under a different license?

The maker says RRDtool and modified versions may not be sold under a license other than the GNU GPL.

Does it offer support?

The maker says RRDtool work is financed through customer-specific add-on features and support contracts.

Facts from RRDtool's own pages

Caching: The documentation describes rrdcached as a data caching daemon for RRDtool. · oss.oetiker.ch, 11 Oct 2026
Consolidation: Built-in classic consolidation functions include AVERAGE, MIN, MAX, and LAST. · oss.oetiker.ch, 11 Oct 2026
Data accuracy limit: The create documentation says pre-filling an RRD makes a best effort to preserve data and does not guarantee data correctness. · oss.oetiker.ch, 11 Oct 2026
Database: RRDtool creates Round Robin Database files with configured data sources and archives. · oss.oetiker.ch, 11 Oct 2026
Data export: RRDtool can export data in XML format from one or several RRD files. · oss.oetiker.ch, 11 Oct 2026
Data retention: Round Robin Archives store a configured number of data values, with older values cycling out as the archive is updated. · oss.oetiker.ch, 11 Oct 2026
Deployment: RRDtool is distributed as source and is also listed with binary distributions for platforms including Debian Linux, Solaris, HP-UX, and Cygwin Windows. · oss.oetiker.ch, 11 Oct 2026
Forecasting: Specialized archives support Holt-Winters smoothing, confidence bands, and aberrant behavior detection. · oss.oetiker.ch, 11 Oct 2026
Interfaces: RRDtool can be integrated in shell scripts and Perl, Python, Ruby, Lua, or Tcl applications. · oss.oetiker.ch, 11 Oct 2026
Language bindings: Perl, Tcl, Ruby, and Python bindings are included in the distribution; the download page also lists PHP and Node.js bindings. · oss.oetiker.ch, 11 Oct 2026
License: RRDtool is available under GNU General Public License V2 or later. · oss.oetiker.ch, 11 Oct 2026
License limitation: The maker says RRDtool or modified versions may not be sold under a license other than the GNU GPL. · oss.oetiker.ch, 11 Oct 2026
Performance: The maker describes RRDtool as a high performance system. · oss.oetiker.ch, 11 Oct 2026
Platforms: The maker says RRDtool compiles on various Linux and Unix platforms and Microsoft Windows. · oss.oetiker.ch, 11 Oct 2026
Purpose: RRDtool is an open source data logging and graphing system for time series data. · oss.oetiker.ch, 11 Oct 2026
Support: The maker says it finances RRDtool work through customer-specific add-on features and support contracts. · oss.oetiker.ch, 11 Oct 2026

Where RRDtool stands on Freedom251

Time-Series Databases#21 of 36