Freedom251 › AI Coding Assistants
rubberduck
What rubberduck is
rubberduck is a web-based coding assistant that helps engineers decide on software design before implementation. A session moves through design, planning and execution, producing a design document, an implementation plan and a pull request for review. The design record keeps decisions, rejected alternatives and reasoning after a feature ships. rubberduck follows codebase data flows to map dependencies and edge cases, then divides approved work into small tasks. Execution runs in an isolated environment built from an image supplied by the user, including databases and test infrastructure. Each completed task receives a detailed code review, and quality gates must pass before a pull request opens. Chat assistance, a coding agent and codebase indexing are included. Tokens use provider rates with 0% markup. Compute is billed per second at $0.0504/vCPU·hr and $0.0162/GiB·hr. Starter is free with 10 sessions monthly; Pro is $30 a month.
Who it suits
rubberduck suits engineers who want documented design decisions, codebase-aware planning and reviewed implementation work. It is available on the web with free and paid session limits.
What it does well
- Design, plan and execution phases
- Records rejected alternatives and reasoning
- Maps dependencies and edge cases
- Isolated execution environments
- Quality gates before pull requests
What to know first
- Starter allows 10 sessions per month
- Pro costs $30 a month
- Compute charges apply per second
- Teams plan is marked Soon
Plans
| Plan | Billed and limits | Price |
|---|---|---|
| Starter | No billing; $0 · 10 sessions per month · design docs are yours · no signup credit | Free |
| Pro | $30 / month; monthly only · Unlimited sessions · design docs are yours · $20 signup credit | $30 a month |
| Teams | Per seat; Teams Soon · Unlimited sessions | $60 a month |
| Teams (Soon) | From $60 / seat; per-seat billing · Unlimited sessions · design docs shared across the team · no signup credit | $60 a month |
As userubberduck.com lists them, read 11 Oct 2026. The maker's own page has the final word.
Verdict
rubberduck links design decisions to planned tasks, isolated execution and pull-request review. The free Starter tier is capped, while Pro offers unlimited sessions for $30 a month; Teams is listed as Soon.
Facts from rubberduck's own pages
- Coding agent
- Yes · userubberduck.com, 22 Sept 2026
- Chat assistance
- Yes · userubberduck.com, 22 Sept 2026
- Codebase indexing
- Yes · userubberduck.com, 22 Sept 2026
- Code review
- Each completed task receives a detailed code review, and quality gates must pass before Rubberduck opens a pull request for review. · userubberduck.com, 11 Oct 2026
- Compute charges
- Execution compute is billed per second at the listed rates of $0.0504/vCPU·hr and $0.0162/GiB·hr. · userubberduck.com, 11 Oct 2026
- Design records
- The product records design decisions, rejected alternatives, and the reasoning behind them in a design document that remains after the feature ships. · userubberduck.com, 11 Oct 2026
- Execution
- It implements tasks in an isolated environment built from an image the user provides, including development dependencies such as databases and test infrastructure. · userubberduck.com, 11 Oct 2026
- Free plan
- Yes · userubberduck.com, 22 Sept 2026
- Machine sizing
- Users choose machine size, with presets as the default. · userubberduck.com, 11 Oct 2026
- Planning
- It follows codebase data flows to map dependencies and edge cases, then breaks approved designs into small tasks for user review. · userubberduck.com, 11 Oct 2026
- Product
- Rubberduck explores software design decisions with the engineer and writes code after the engineer has made those decisions. · userubberduck.com, 11 Oct 2026
- Signup
- The registration page asks for a preferred name, email, and password of at least eight characters. · userubberubberduck.com, 11 Oct 2026
- Team availability
- The Teams plan is marked “Soon” and offers design docs shared across the team. · userubberduck.com, 11 Oct 2026
- Token charges
- Tokens are billed at the provider’s rates with 0% markup on every plan. · userubberduck.com, 11 Oct 2026
- Workflow
- A session has design, plan, and execution phases, with a reviewable design document, implementation plan, and pull request. · userubberduck.com, 11 Oct 2026
Where rubberduck stands on Freedom251
- AI Coding Assistants#75 of 103