The equation is given as \( x^4 + 1 = 0 \), which simplifies to:
\[
x^4 = -1
\]
The fourth roots of \( -1 \) are the complex numbers that satisfy this equation. These roots are given by:
\[
x = e^{i\frac{(2n+1)\pi}{4}} \quad {for} \quad n = 0, 1, 2, 3
\]
The four roots are:
\[
x = e^{i\frac{\pi}{4}}, \, e^{i\frac{3\pi}{4}}, \, e^{i\frac{5\pi}{4}}, \, e^{i\frac{7\pi}{4}}
\]
The product of these roots can be found by multiplying all the roots. Since the product of the roots of a polynomial \( ax^n + bx^{n-1} + \cdots + z = 0 \) is given by \( (-1)^n \times \frac{{constant term}}{{leading coefficient}} \), for this equation, the product of the roots is \( (-1)^4 \times \frac{1}{1} = 1 \).
Thus, the product of the roots is \( \boxed{1} \).