The design of tokenomics, i.e., distribution and circulation mechanisms of cryptocurrency tokens, is a top priority for almost all Web3 applications which relates to their own economic systems via native cryptocurrency tokens. Unfortunately, while the sustainability of tokenomics largely determines the long-term development of a Web3 application, the tooling support for the design of it has been far too insufficient. A common practice at the time of writing is to specify tokenomics with a combination of documents, spreadsheets, code scripts etc.. In this paper, we introduce the TMI development platform for the modelling and analysis of Web3 tokenomics. TMI creates a domain-specific language and its graphical development environment for developers to succinctly model crypto-economic relations in a drag-and-drop way. Based on created models, TMI allows developers to formally analyse their tokenomics via checking fundamental economic properties, e.g., The core team of a project holds less than 20% of the project token in 36 months. A demonstration video of TMI is available at.