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Welcome to REBOUND

REBOUND Examples

REBOUND is an N-body integrator, i.e. a software package that can integrate the motion of particles under the influence of gravity. The particles can represent stars, planets, moons, ring or dust particles. REBOUND is very flexible and can be customized to accurately and efficiently solve many problems in astrophysics.

REBOUND 24 Meeting

REBOUND 24 Virtual Meeting

Join us for the first virtual 2-day REBOUND meeting, aimed to bring REBOUND developers and users together. 1 day of science talks, 1 day of technical/hands-on talks, discussions on REBOUND's future + social events!

Abstract submission and registration are now open at


  • No dependencies on external libraries.
  • Runs natively on Linux, MacOS, and Windows.
  • Symplectic integrators (WHFast, SEI, LEAPFROG, EOS)
  • Hybrid symplectic integrators for planetary dynamics with close encounters (MERCURIUS)
  • High order symplectic integrators for integrating planetary systems (SABA, WH Kernel methods)
  • High accuracy non-symplectic integrator with adaptive time-stepping (IAS15)
  • Can integrate arbitrary user-defined ODEs that are coupled to N-body dynamics for tides, spin, etc
  • Support for collisional/granular dynamics, various collision detection routines
  • The computationally intensive parts of the code are written entirely in C, conforming to the ISO standard C99, and can be used as a thread-safe shared library
  • Easy-to-use Python module, installation in 3 words: pip install rebound
  • Real-time, 3D visualization, for both C and Python.
  • Extensive set of example problems for both C and Python. You can run examples directly from your browser without the need to download or install anything.
  • Parallelized WHFast512 integrator for super fast integrations of planetary systems with SIMD AVX512 instructions
  • Parallelized with OpenMP (for shared memory systems)
  • Parallelized with MPI is supported for some special use cases only (using an essential tree for gravity and collisions)
  • The code is 100% open-source. All features are included in the public repository on github


REBOUND is open source and you are invited to contribute to this project!

YouTube tutorials

There are several short YouTube videos describing various aspects of REBOUND available at

Additional physics

To easily incorporate additional physics modules such as migration forces, GR effects and spin into your REBOUND simulations, see REBOUNDx at

Analytical and semianalytical tools

If you're interested in comparing numerical simulations to analytical and semianalytical tools for celestial mechanics, see Celmech at

Ephemeris-quality integrations of test particles

To generate ephemeris-quality integrations of test particles in the Solar System with a precision on par with JPL's small body integrator, see ASSIST at


There are several papers describing the functionality of REBOUND.

  1. Rein & Liu 2012 (Astronomy and Astrophysics, Volume 537, A128) describes the code structure and the main feature including the gravity and collision routines for many particle systems.

  2. Rein & Tremaine 2011 (Monthly Notices of the Royal Astronomical Society, Volume 415, Issue 4, pp. 3168-3176) describes the Symplectic Epicycle integrator for shearing sheet simulations.

  3. Rein & Spiegel 2015 (Monthly Notices of the Royal Astronomical Society, Volume 446, Issue 2, p.1424-1437) describes the versatile high order integrator IAS15 which is now part of REBOUND.

  4. Rein & Tamayo 2015 (Monthly Notices of the Royal Astronomical Society, Volume 452, Issue 1, p.376-388) describes WHFast, the fast and unbiased implementation of a symplectic Wisdom-Holman integrator for long term gravitational simulations.

  5. Rein & Tamayo 2016 (Monthly Notices of the Royal Astronomical Society, Volume 459, Issue 3, p.2275-2285) develop the framework for second order variational equations.

  6. Rein & Tamayo 2017 (Monthly Notices of the Royal Astronomical Society, Volume 467, Issue 2, p.2377-2383) describes the Simulationarchive for exact reproducibility of N-body simulations.

  7. Rein & Tamayo 2018 (Monthly Notices of the Royal Astronomical Society, Volume 473, Issue 3, p.3351–3357) describes the integer based JANUS integrator.

  8. Rein, Hernandez, Tamayo, Brown, Eckels, Holmes, Lau, Leblanc & Silburt 2019 (Monthly Notices of the Royal Astronomical Society, Volume 485, Issue 4, p.5490-5497) describes the hybrid symplectic integrator MERCURIUS.

  9. Rein, Tamayo & Brown 2019 (Monthly Notices of the Royal Astronomical Society, Volume 489, Issue 4, November 2019, Pages 4632-4640) describes the implementation of the high order symplectic integrators SABA, SABAC, SABACL, WHCKL, WHCKM, and WHCKC.

  10. Javaheri, Rein & Tamayo 2023 (The Open Journal of Astrophysics, Volume 6, July 2023) describes the WHFast512 integrator which uses AVX512 instructions.


If you use this code or parts of this code for results presented in a scientific publication, we would greatly appreciate a citation. please cite REBOUND. The simplest way to find the citations relevant to the specific setup of your REBOUND simulation is:

sim = rebound.Simulation()
-your setup-


When you cite one of the REBOUND papers, your paper will receive an automatic shout-out from the REBOUND Citation Bot.


REBOUND is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

REBOUND is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with REBOUND. If not, see