eCapital Software Engineer interview questions

Initial screen, Tech round with director and then a take home CRUD task. in last round explain the crud app, extend design/feature, tech details, basic tech concepts and some SQL tasks. Offered below the average listed on glassdoor for the same position. Asked for any scope of negotiation with a very positive and flexible mail. They ghosted for a week and then suddenly sent a mail saying they rescinded the offer saying no scope for negotiation. This seemed super unprofessional as the language in my email was very soft and flexible. However, the director and the tech people seemed nice, and the interviews were friendly.