Feynman vs Kopai: Features, Pricing & Which Is Better (2026)
A side-by-side comparison of Feynman and Kopai — features, pricing, and ideal use cases — to help you decide which AI tool fits your workflow.
Feynman
Companion
Open-source AI research agent that reads papers, ranks literature, drafts research and plans experiments from the terminal or a local workbench.
Key features
- Cited Research Briefs: Asking a research question returns a synthesized brief where each claim is tied to the paper or web source it came from, rather than an unsourced summary.
- PaperRank Scoring: Ranks papers on a topic with transparent evidence for citations, methodology, reproducibility and provenance so reading order is a decision you can inspect.
- Paper Access Resolver: Resolves a single DOI, arXiv ID, OpenAlex ID, PMID, PMCID or title against OpenAlex, arXiv/alphaXiv, DOI and Europe PMC, with optional full-text fetching.
- Local Science Workbench: `feynman serve` opens a standalone app with projects, sessions, chat, notebooks, compute, artifact previews and provenance in one place.
- Claim Auditing and Replication: Compares a paper's stated claims against what its code actually does, and generates replication plans with compute targets and gated experiment steps.
- Local and Hosted Models: Works with hosted providers via OAuth or API key and with local runtimes including LM Studio, Ollama, vLLM and a LiteLLM proxy.
- Skills-Only Install: The research skill library can be installed on its own into Claude, Codex or OpenCode projects without the terminal app or bundled runtime.
- Science Artifacts: Reports, data files, spreadsheets, notebooks, LaTeX, chemistry sketches and genomes are browsable together with versions, lineage and execution logs.
Best for
- Deciding What to Read: Ranking a fresh literature pile on a topic by reproducibility and methodology instead of citation count alone.
- Writing a Literature Review: Producing a review that separates where the field agrees from where questions remain open, with citations attached.
- Verifying a Paper's Claims: Auditing whether the results a paper reports are supported by the code and data it released.
- Planning a Replication: Turning a published finding into a concrete replication plan with a compute target and staged experiment steps.
- Running Deep Research Passes: Launching a multi-agent deep dive on a topic that synthesizes findings and verifies them before reporting.
- Keeping Research Local: Running the whole pipeline against a local model so unpublished work and private data never leave the machine.
- Adding Research Skills to a Coding Agent: Installing the skills bundle into an existing Claude or Codex project to get research workflows without a second app.
Kopai
Kopai
Serverless cloud for building, hosting, and monetizing domain-specialized AI agents, with RAG, orchestration, and per-message billing handled for you.
Key features
- Prompt-to-Agent Builder: Write a prompt, upload documents, and try several models side by side — seven steps from blank page to a shipped agent.
- Managed Infrastructure: Kopai holds the model keys, runs the vector database, and keeps the servers alive; you get an endpoint and a readable bill.
- Agent Marketplace: List an agent and get paid per message, keeping 70% of your markup, with every charge logged in an auditable ledger.
- Multi-Model Gateway: One integration across GPT-4o, Kimi K2, Gemini 2.5, Qwen 3, and DeepSeek, switchable at any time.
- Automatic Document Indexing: Upload PDF, DOCX, or XLSX files and Kopai indexes them and handles retrieval behind the scenes.
- Resilient Streaming: Answers resume from where they stopped after a dropped connection or closed tab, with no tokens lost.
- Conversational Agent Creation: Describe the job in ordinary chat and Kopai drafts the agent, picks its organization, and finishes on your approval.
- Kopai for Teams: Seats and roles, team-private agents, shared knowledge, and usage numbers you can check.
Best for
- A lawyer packages case-preparation expertise into an agent and sells access on the marketplace instead of billing hours.
- A consultant turns a library of internal documents into a domain expert clients can query directly.
- A solo creator wants to ship a RAG agent without standing up a vector database or backend service.
- A SaaS company embeds a specialized agent in its own product while letting Kopai handle billing and payouts.
- A team needs private internal agents with role-based access over a shared knowledge base.
- A developer wants to test the same agent across several model providers before committing to one.