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Top 23 prompt-engineering Open-Source Projects
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ponytail
Makes your AI agent think like the laziest senior dev in the room. The best code is the code you never wrote.
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AppSignal
Monitoring that respects your time & budget. APM, error tracking, and dashboards for modern web apps. Ten-minute setup, transparent flat pricing, and support from engineers who actually use the product.
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View on GitHub
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caveman
🪨 why use many token when few token do trick — Claude Code skill that cuts 65% of tokens by talking like caveman
Project mention: Caveman Ultra Mode: Make Your Coding Agent Say Less, Not Think Less | dev.to | 2026-08-29Caveman is a skill/plugin built around that distinction. It makes a coding agent communicate in short, direct language its deliberately rough “caveman-speak” while aiming to leave code, commands, and errors byte-for-byte intact. The project describes this as making the agent’s mouth smaller rather than its brain smaller.
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Prompt-Engineering-Guide
🐙 Guides, papers, lessons, notebooks and resources for prompt engineering, context engineering, RAG, and AI Agents.
Project mention: Node.js Moderation Control: Large Volume User Content Through Batch LLM Triage | dev.to | 2026-08-25 -
headroom
Compress tool outputs, logs, files, and RAG chunks before they reach the LLM. 20% fewer tokens for coding agents, 60-95% fewer tokens for JSON, same answers. Library, proxy, MCP server.
Project mention: Headroom: Save Tokens from Reversible Compression | news.ycombinator.com | 2026-09-04 -
system_prompts_leaks
Extracted system prompts from Anthropic - Claude Fable 5, Opus 5, Claude Design, Claude Code. OpenAI - ChatGPT GPT-5.6-Sol, Codex. Google - Gemini 3.5 Flash, 3.1 Pro, Antigravity. xAI - Grok, Cursor, Copilot, VS Code, Perplexity, and more. Updated regularly.
I compared the Claude Opus 4.8 and 5 system prompts, as well as the Claude Code Opus 4.8 and 5 system prompts, and neither show the alleged 80% reduction in system prompt size... Is the Claude Code system prompt leak incorrect? Do I not know what 80% looks like? Why such a large lie (so it seems)?
Claude Code prompt leaks: https://github.com/asgeirtj/system_prompts_leaks/tree/main/A...
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CL4R1T4S
LEAKED SYSTEM PROMPTS FOR CHATGPT, CLAUDE, GEMINI, GROK, PERPLEXITY, CURSOR, LOVABLE, REPLIT, AND MORE! - AI SYSTEMS TRANSPARENCY FOR ALL! 👐
Project mention: What a 275K-Character Claude Prompt Teaches Us About Building AI Agents | dev.to | 2026-09-02The document appeared in Pliny the Liberator’s CL4R1T4S GitHub repository, which collects system prompts and jailbreak-related material from several AI products.
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Kargo
Stop Scripting Promotions. Start Shipping with Kargo. Kargo automates promotion across dev, staging, and prod with approval gates and verification. Open source, built by the team behind Argo CD. Download now.
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agents
Multi-harness agentic plugin marketplace for Claude Code, Codex, Cursor, OpenCode, GitHub Copilot, and Google Antigravity
Project mention: Skills Sprawl: When Too Much of a Good Thing Confuses Your AI Agent | dev.to | 2026-08-17Specialised & Community Skills: Niche skills sourced from specific community repositories, including wshobson/agents (documentation-and-adrs, interview-me), coreyhaines31/marketingskills (seo-audit), remotion-dev/skills (remotion-best-practices), and vercel-labs/skills (find-skills).
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awesome-copilot
Community-contributed instructions, agents, skills, and configurations to help you make the most of GitHub Copilot.
Project mention: GPT-5.6 launched and developers immediately hit their usage limits. The fix is not a bigger plan | dev.to | 2026-07-105. context-map - 9,357 installs (GitHub) Generate a precise map of relevant files, dependencies and tests up front, so the agent navigates instead of exploring. Exploration is the silent budget killer: every wrong file opened is paid for again in every later turn that carries it.
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langfuse
🪢 Open source AI engineering platform: LLM evals, observability, metrics, prompt management, playground, datasets. Integrates with OpenTelemetry, LangChain, OpenAI SDK, LiteLLM, and more. 🍊YC W23
Project mention: How to change an LLM prompt in production without a code deploy | dev.to | 2026-08-30Langfuse is the other serious option in this category if you also want observability, evals and traces bundled with prompt management. Different scope, more setup, worth comparing honestly.
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MLflow
The open source AI engineering platform for agents, LLMs, and ML models. MLflow enables teams of all sizes to debug, evaluate, monitor, and optimize production-quality AI applications while controlling costs and managing access to models and data.
Project mention: MLflow CVE-2026-64849: Cloud Credential Theft via Webhook SSRF | dev.to | 2026-08-20Original Source: MLflow Security Advisory / CISA
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12-factor-agents
What are the principles we can use to build LLM-powered software that is actually good enough to put in the hands of production customers?
Project mention: 12-Factor Agents – Principles for building reliable LLM applications | news.ycombinator.com | 2026-08-16 -
claude-skills
380 Claude Code skills & agent skills & plugins (30+ Agents, 70+ custom commands, 380+ skills, customizable references, scripts)for Claude Code, Codex, Gemini CLI, Cursor, and 8 more coding agents — engineering, marketing, product, compliance, C-level advisory, research, business operations, commercial & finance, and your daily productivity skills.
Project mention: I Built a Dual-Pool Adversarial Review System for AI Agents — And It Actually Works | dev.to | 2026-06-27I tested this on my own PR to alirezarezvani/claude-skills (18.7K stars):
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promptfoo
Test your prompts, agents, and RAGs. Red teaming/pentesting/vulnerability scanning for AI. Compare performance of GPT, Claude, Gemini, DeepSeek, and more. Simple declarative configs with command line and CI/CD integration. Used by OpenAI and Anthropic.
Primary references: GitHub Spec Kit, Promptfoo assertions, Qwen Code, Goose, Chrome DevTools MCP, MarkItDown MCP, Renovate, and Semgrep CLI.
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opik
Debug, evaluate, and monitor your LLM applications, RAG systems, and agentic workflows with comprehensive tracing, automated evaluations, and production-ready dashboards.
Project mention: AcruxCore alternatives - langfuse, phoenix-on-azure, phoenix, opik, and MLflow | libhunt.com/r/AcruxCore | 2026-08-14 -
FinGPT
FinGPT: Open-Source Financial Large Language Models! Revolutionize 🔥 We release the trained model on HuggingFace.
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Project mention: AcruxCore alternatives - langfuse, phoenix-on-azure, phoenix, opik, and MLflow | libhunt.com/r/AcruxCore | 2026-08-14
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promptflow
Build high-quality LLM apps - from prototyping, testing to production deployment and monitoring.
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loop-engineering
Practical patterns, starters & CLI tools for loop engineering with AI coding agents. Design systems that prompt and orchestrate agents (inspired by Addy Osmani and Boris Cherny). Includes loop-audit, loop-init, loop-cost.
Meanwhile, the ecosystem materialized. obra/superpowers shipped a complete software development methodology built on composable skills — 1,276+ stars and growing. The cobusgreyling/loop-engineering repo cataloged patterns from Osmani and Cherny into a practical reference.
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chatgpt_system_prompt
A collection of GPT system prompts and various prompt injection/leaking knowledge.
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SaaSHub
SaaSHub - Software Alternatives and Reviews. SaaSHub helps you find the best software and product alternatives
NOTE:
The open source projects on this list are ordered by number of github stars.
The number of mentions indicates repo mentiontions in the last 12 Months or
since we started tracking (Dec 2020).
prompt-engineering discussion
prompt-engineering related posts
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Node.js Moderation Control: Large Volume User Content Through Batch LLM Triage
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Fintech Node.js Speech-to-Text: 4 Timeout Gates for Large Multipart Audio
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AcruxCore alternatives - langfuse, phoenix-on-azure, phoenix, opik, and MLflow
6 projects | 14 Aug 2026 -
Developers are installing taste: 4 of today's 7 fastest-rising Claude Code skill searches are design skills
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My Node.js Text-to-Image Gate: A Web App API Contract Test
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Show HN: Sufleur-style prompt registry with typed code-generation
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I obtained Claude Opus 5 system prompt
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A note from our sponsor - AppSignal
www.appsignal.com | 8 Sep 2026
Index
What are some of the best open-source prompt-engineering projects? This list will help you:
| # | Project | Stars |
|---|---|---|
| 1 | ponytail | 129,797 |
| 2 | generative-ai-for-beginners | 119,162 |
| 3 | caveman | 102,695 |
| 4 | Prompt-Engineering-Guide | 77,992 |
| 5 | headroom | 69,198 |
| 6 | system_prompts_leaks | 64,174 |
| 7 | CL4R1T4S | 48,956 |
| 8 | agents | 39,447 |
| 9 | awesome-copilot | 38,630 |
| 10 | langfuse | 34,207 |
| 11 | prompt-optimizer | 33,976 |
| 12 | MLflow | 27,795 |
| 13 | 12-factor-agents | 25,692 |
| 14 | claude-skills | 25,513 |
| 15 | promptfoo | 24,844 |
| 16 | opik | 21,797 |
| 17 | FinGPT | 21,205 |
| 18 | outlines | 15,743 |
| 19 | awesome-chatgpt-zh | 11,679 |
| 20 | phoenix | 11,318 |
| 21 | promptflow | 11,234 |
| 22 | loop-engineering | 10,999 |
| 23 | chatgpt_system_prompt | 10,751 |
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APM, error tracking, and dashboards for modern web apps. Ten-minute setup, transparent flat pricing, and support from engineers who actually use the product.
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