Let $$d\ge 2$$
d
≥
2
. In this paper we give a simple proof of the endpoint Besov-Lorentz estimate $$\begin{aligned} \Vert I_\alpha F\Vert _{{\dot{B}}^{0,1}_{d/(d-\alpha ),1}(\mathbb {R}^d;\mathbb {R}^k)} \le C \Vert F \Vert _{L^1(\mathbb {R}^d;\mathbb {R}^k)} \end{aligned}$$
‖
I
α
F
‖
B
˙
d
/
(
d
-
α
)
,
1
0
,
1
(
R
d
;
R
k
)
≤
C
‖
F
‖
L
1
(
R
d
;
R
k
)
for all $$F \in L^1(\mathbb {R}^d;\mathbb {R}^k)$$
F
∈
L
1
(
R
d
;
R
k
)
which satisfy a first order cocancelling differential constraint, where $$\alpha \in (0,d)$$
α
∈
(
0
,
d
)
and $$I_\alpha $$
I
α
is a Riesz potential. We show how this implies endpoint Besov–Lorentz estimates for Hodge systems with $$L^1$$
L
1
data via fractional integration for exterior derivatives.