  We show that, given a Banach space $X$, the Lipschitz-free space over $X$,
denoted by $\mathcal{F}(X)$, is isomorphic to $(\sum_{n=1}^\infty
\mathcal{F}(X))_{\ell_1}$. Some applications are presented, including a
non-linear version of Pelczy\'ski's decomposition method for Lipschitz-free
spaces and the identification up to isomorphism between
$\mathcal{F}(\mathbb{R}^n)$ and the Lipschitz-free space over any compact
metric space which is locally bi-Lipschitz embeddable into $\mathbb{R}^n$ and
which contains a subset that is Lipschitz equivalent to the unit ball of
$\mathbb{R}^n$. We also show that $\mathcal{F}(M)$ is isomorphic to
$\mathcal{F}(c_0)$ for all separable metric spaces $M$ which are absolute
Lipschitz retracts and contain a subset which is Lipschitz equivalent to the
unit ball of $c_0$. This class contains all $C(K)$ spaces with $K$ infinite
compact metric (Dutrieux and Ferenczi had already proved that
$\mathcal{F}(C(K))$ is isomorphic to $\mathcal{F}(c_0)$ for those $K$ using a
different method). Finally we study Lipschitz-free spaces over certain unions
and quotients of metric spaces, extending a result by Godard.
