We aimed to provide a systematic overview of freely available tools which may help to plan or monitor costs for randomised clinical trials (RCTs).We systematically searched MEDLINE, EMBASE and EconLit and conducted internet searches via Google (last search October 2018). We included all freely available tools and determined their specific purpose, which parts of clinical trial projects and which types of costs they covered, and if they were user tested or validated in any form.We identified 25 available tools. Most tools were downloadable on websites from institutions related to clinical research. Seven tools were developed to plan the budget for an entire RCT, 17 tools for calculating budgets of an individual trial centre, and one tool for monitoring costs of ongoing RCTs. 18 tools considered fixed, variable, and indirect costs. Only two tools were clearly user tested or validated.Several freely available tools aim to support investigators in planning costs of an entire trial or in planning the budget for a clinical trial site. How valid and useful they are remains to be shown for most of them. Future tools should be openly shared, user tested, and validated.