Xcas does solve differential equations
Xcas is a user interface to Giac, which is a free,open source basic Computer Algebra System (CAS) for Microsoft Windows, Apple macOS, Linux, and FreeBSD; Xcas is written in C++. Giac can be used directly inside software written in C++.
Giac has a compatibility mode with WolframAlpha,Mathematica, Maple,MuPAD, Matlab, Yacas, SageMath, Qcas, ExpressionsinBar (64 bit app for macOS) and Magma, CPMP-Tools, WordMat (addon to Microsoft Word) software and TI-89, TI-92, Voyage 200 and TI-Nspire calculators. Users can use Giac/Xcas as well as a free software compatible with Maple to develop formal algorithms or use it in other software. Xcas is used in SageMath for calculus operations. Among other things Xcas can solve equations and draw graphs. There is a forum for questions about Xcas.
CmathOOoCAS, an OpenOffice.org plugin which allows formal calculation in Calc spreadsheet and Writer word processing, uses Xcas to perform calculations.
Here is a brief overview of what Xcas is able to do:
Some Xcas commands
- propfrac(42/15) = 2 + 4/5
- Calculate square root = sqrt(4) = 2
- Draw a vertical line in coordinate system: line( =1) = the vertical line =1
- Draw graph: plot(function)
- Calculate average: mean([3, 4, 2]) = 3
- Calculate variance: variance([3, 4, 2]) = 2/3
- Calculate standard deviation: stddev([3, 4, 2]) = sqrt(2/3)
- Calculate determinant of a matrix: det([[1,2], [3,4]]) = -2
- Calculate local extrema of a function: extrema(-2*cos()-cos()^2,) = , [pi]
- Calculate cross product of two vectors: cross([1, 2, 3], [4, 3, 2]) = [-5, 10, -5]
- Calculate permutations: nPr
- Calculate combinations: nCr
- Solve equation: solve(equation,)
- Factoring Polynomial: factor(polynomial,) or cfactor(polynomial,)
- Differentiation of function: diff(function,)
- Calculate integral aka antiderivative: int(function,)
- Calculate definite integral aka area under curve: int(function,,lowerlimit,upperlimit)
- Calculate definite integral aka solid of revolution - finding volume by rotation (around the axis): int(pi*function^2,,lowerlimit,upperlimit)
- Calculate definite integral aka Solid of Revolution - finding volume by rotation (around the axis) for a decreasing function: int(2*pi**function,,lowerlimit,upperlimit)
- Separation of variables: split((+1)*(-2),[,]) = [+1,-2]
- desolve differential equation (right side of Differential Equation written as or ): desolve(differential equation,)
or read more commands and features here: http://www-fourier.ujf-grenoble.fr/~parisse/giac/cascmd_en.pdf
Xcas works for these operating Systems
Xcas and Giac are open-source projects  developed by Bernard Parisse et al. at the Joseph Fourier University of Grenoble (Isère), France, since 2000. Xcas and Giac are based on experiences gained with Parisse's former project Erable.
In 2013 the mathematical software Xcas was also integrated into GeoGebra's CAS view.
Since 2013 there are videos showing how Xcas works.
Pocket CAS and CAS Calc P11 utilize Giac.
The system was also chosen by Hewlett-Packard as the CAS for their HP Prime calculator, which utilizes the Giac/Xcas 1.4.9 engine under a dual-license scheme.