Replit Agent prototypes Budget Buddy
Justin Tan reports Replit Agent producing Budget Buddy from a detailed brief, then reaching a working budgeting prototype after seven or eight additional prompts.
Original prompt
Shared by the source author. See source notes for context.
Develop a simple budgeting tool with a clean, responsive interface that includes three main functionalities.
Reach people exploring AI agents
See placements →Evidence at a glance
Sourced account- Source author
- Justin Tan
- Original account
- Read the source ↗
- Published
- 7 Jan 2025
- Source link checked
- 15 Oct 2026
- Reported result
- Justin Tan reports Replit Agent producing Budget Buddy from a detailed brief, then reaching a working budgeting prototype after seven or eight additional prompts.
- Human involvement
- Tan specifies requirements and reviews several prompt-driven revisions. The prototype is not an independently audited financial application.
A linked account supports attribution. It does not mean we independently reproduced its result.
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How the agent did it
- Tan gives Replit Agent a detailed brief for budgets, charts, expenses and local persistence.
- The agent generates a first-pass application.
- Tan directs seven or eight further revisions over about twenty minutes.
Justin Tan tested Replit Agent with a small budgeting application before using it for a larger newsletter project. His initial brief specified three views: category budgets, spending charts and an expense-entry form. It also required data to persist locally between sessions.
Replit Agent generated the first version from that single detailed brief. Tan then used seven or eight further prompts over about twenty minutes to revise it. He presents the result as a functioning Budget Buddy prototype, with a screenshot of its home page, and describes roughly thirty minutes for the test overall.
The output should be understood at that scope. The source establishes a working prototype as assessed by its author; it does not provide a financial audit, external user deployment or a long-term check of every persistence and calculation path. The detailed brief names the expected screens and fields, giving the owner concrete behavior to inspect after generation.
Tan's later experience on a different application also found stalled editing and claimed changes missing from code. Those failures are not attributed to Budget Buddy, but they explain why he retained active review. In this test the author specified the product and supplied the follow-up direction rather than merely accepting the first generated interface.
Prompt
Original prompt
Source: justinyjtan.substack.com · Justin Tan
Frequently asked questions
Was it finished from one prompt?
The first pass came from one prompt, but the working prototype followed seven or eight additional prompts.
Which views were requested?
Category budgeting, a chart dashboard and an expense-entry page.
Was a bank connection demonstrated?
No. This budgeting test specified local data persistence, not linked bank data.
More details
Remaining steps
- He reports a working Budget Buddy prototype and publishes a screenshot.
About this account
Replit Agent generated the budgeting interface, expense logging, charts and local persistence, then revised the prototype through follow-up requests.
Firsthand account opened and read. Outcome is source-reported, not independently reproduced. Budget Buddy is the preliminary test within the source; separate newsletter failures are not presented as bugs in this app. Original prompt/instruction excerpt from the published account; shortened to no more than 25 quoted words.
Credit: Justin Tan
Source published 7 Jan 2025
Source checked 15 Oct 2026
Tools and topics
Replit Agent · Budget Buddy · Local storage
Replit Agent · Budget Buddy · Local storage
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.