In the realm of embedded critical systems, it is crucial to guarantee the correctness of programs before they are deployed. Static analyzers can help by detecting at compile-time potentially erroneous program behaviors: they perform sound over-approximations to achieve an efficient analysis while not missing any potential behavior. We discuss the systematic design of such analyzers using abstract interpretation, a general theory of semantic approximation. After recalling the classic construction of static analyzers for sequential programs by abstraction of the concrete trace semantics, we introduce abstractions to derive thread-modular analyzers for multithreaded programs, borrowing ideas from rely/guarantee proof methods. Finally, we present two static analyzer tools, Astrée and AstréeA, that are used to check for run-time errors in large sequential and multithreaded embedded industrial avionic C applications.