Objective: To co-design and test the acceptability of a peer-led web-based resource (PLWR) for cancer carers to provide practical and emotional advice on common issues. Methods: A six-step co-design model informed PLWR development. Content was developed through three cancer carer workshops and monthly meetings with an expert advisory team (n = 12). User-testing was conducted via web-based survey and telephone interview. Descriptive statistics and thematic analysis were utilised.