The official specification for WebAssembly includes an end-to-end formal semantics, and every new feature must be specified in this formal semantics, in prose, and in the official reference interpreter before it can be standardised. This manual process with its redundancies is laborious and error-prone. We present SpecTec, a DSL and toolchain that facilitates both the WebAssembly specification and the generation of artefacts necessary for standardisation. A definition of the WebAssembly semantics in SpecTec serves as a single source of truth, from which we can generate a typeset specification, including formal definitions and prose pseudocode descriptions, and a meta-level interpreter. Further backends for test generation and meta-theory in theorem provers are work in progress.