ChunkBack
A Fake LLM API server for testing apps without paying
Details
- External ID
- 45981310
- Source
- HN
- Company
- —
- Product
- ChunkBack
- Website domain
- github.com
- Launched
- Nov. 19, 2025
- Cohort
- —
- Upvotes
- 6
- Upvotes percentile
- 0.27074235807860264
- Tags
- —
- Fetched at
- Sept. 7, 2026, 9:25 p.m.
- Updated at
- Sept. 7, 2026, 9:25 p.m.
Description
Hi HN,I've been working with LLMs in production for a while both as a solo dev building apps for clients and working at an AI startup. The one thing that always was a pain was to pay OpenAI/Gemini/Anthropic a few dollars a month just for me to say "test" or have a CI runner validate some UI code. So I built this server called ChunkBack, that mocks the popular llm provider's functionality but allows you to type in a deterministic language:`SAY "cheese"` or `TOOLCALL "tool_name" {} "tool response"`I've had to work in some test environments and give good results for experimenting with CI, but it's still an early project so would love feedback and more testers on.
Enrichment
- Theme
- lightweight and on-device AI runtimes
- Vertical
- Horizontal
- Function
- Dev tools
- Audience
- Developer
- AI stance
- Not AI
- Project type
- Hobby / open-source project
- Normalized one-liner
- mock llm api server for testing
- Manually corrected
- False
Could you build this?
Yes It is a mock HTTP proxy/server mimicking OpenAI/Anthropic/Gemini streaming responses, which can be implemented in a day using Express, FastAPI, or similar frameworks.
Discussion
No comments on this launch.
Competitors
Other products that read as similar to this one — 94 launches clear the similarity bar, closest 8 shown.
Attention rank: #72 of 95 (itself plus its competitors, highest first — normalized so YC and Product Hunt are compared fairly).
Launched 18 days after the earliest competitor.
- LMMOCK · github · 2026-09-20 · 35 upvotes · similarity 0.46
- An unmetered LLM API–$6/month, no token tracking, no limits · hn · 2026-07-06 · 12 upvotes · similarity 0.46
- ChunkHound, a local-first tool for understanding large codebases · hn · 2026-01-17 · 114 upvotes · similarity 0.45
- Mocktail · hn · 2026-08-14 · 25 upvotes · similarity 0.44
- Tokenflood · hn · 2025-11-12 · 21 upvotes · similarity 0.41
- I'm tired of my LLM bullshitting. So I fixed it · hn · 2026-01-22 · 5 upvotes · similarity 0.40
- Why write code if the LLM can just do the thing? (web app experiment) · hn · 2025-11-01 · 436 upvotes · similarity 0.39
- Gerbil · hn · 2025-11-11 · 37 upvotes · similarity 0.39
Other launches for this product
- No other launches for this product.
Same idea, different domain
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