# Standards compared 50 head-to-heads Side-by-side comparisons of agentic web standards that are often confused, often paired, or compete for the same job. Every cell comes from the two records; nothing is editorial. - [Agent2Agent Protocol vs Model Context Protocol](/compare/a2a-vs-mcp/) Coordinate / Act - [x402 vs Agent Payments Protocol](/compare/x402-vs-ap2/) Pay - [x402 vs Machine Payments Protocol](/compare/x402-vs-mpp/) Pay - [x402 vs L402](/compare/x402-vs-l402/) Pay - [Agent Payments Protocol vs Agentic Commerce Protocol](/compare/ap2-vs-agentic-commerce-protocol/) Pay - [Universal Commerce Protocol vs Agentic Commerce Protocol](/compare/ucp-vs-agentic-commerce-protocol/) Pay - [llms.txt vs AGENTS.md](/compare/llms-txt-vs-agents-md/) Read - [llms.txt vs Agentic Resource Discovery](/compare/llms-txt-vs-ard/) Read / Discover - [AGENTS.md vs agents.txt](/compare/agents-md-vs-agents-txt/) Read / Discover - [Agentic Resource Discovery vs api-catalog: A Well-Known URI and Link Relation to Help Discovery of APIs](/compare/ard-vs-api-catalog-rfc9727/) Discover - [Agentic Resource Discovery vs AI Catalog well-known file](/compare/ard-vs-ai-catalog-well-known-file/) Discover - [Agent Client Protocol vs Agentic Commerce Protocol](/compare/agent-client-protocol-vs-agentic-commerce-protocol/) Act / Pay - [Agent Client Protocol vs Agent Communication Protocol](/compare/agent-client-protocol-vs-agent-communication-protocol/) Act / Coordinate - [Agent2Agent Protocol vs Agent Communication Protocol](/compare/a2a-vs-agent-communication-protocol/) Coordinate - [Model Context Protocol vs WebMCP](/compare/mcp-vs-webmcp/) Act - [Model Context Protocol vs Agent Client Protocol](/compare/mcp-vs-agent-client-protocol/) Act - [A2UI (Agent to UI) Protocol vs Agent-User Interaction Protocol](/compare/a2ui-vs-ag-ui/) Present - [MCP Apps vs OpenAI Plugins (formerly Apps SDK)](/compare/mcp-apps-vs-openai-apps-sdk-manifests/) Present / Act - [MCP Server Cards (SEP-2127) vs Agentic Resource Discovery](/compare/mcp-server-cards-vs-ard/) Discover - [Web Bot Auth HTTP Message Signatures vs HTTP Message Signatures](/compare/webbotauth-vs-http-message-signatures/) Identify - [Web Bot Auth HTTP Message Signatures vs SPIFFE (Secure Production Identity Framework for Everyone)](/compare/webbotauth-vs-spiffe/) Identify - [SPIFFE (Secure Production Identity Framework for Everyone) vs Workload Identity in Multi System Environments (WIMSE) Architecture](/compare/spiffe-vs-wimse/) Identify - [Agent Identity and Discovery vs DNS for AI Discovery](/compare/aid-vs-dns-aid/) Discover - [ERC-8004: Trustless Agents vs Agent Name Service v2 (ANS)](/compare/erc-8004-vs-ans/) Identify - [Agent Identity and Discovery vs Agent2Agent Protocol](/compare/aid-vs-a2a/) Discover / Coordinate - [Text and Data Mining Reservation Protocol vs AIPREF Vocabulary](/compare/tdmrep-vs-aipref-vocabulary/) Permit - [Really Simple Licensing vs AIPREF Vocabulary](/compare/rsl-vs-aipref-vocabulary/) Permit - [Content Signals Policy vs AIPREF Vocabulary](/compare/cloudflare-content-signals-policy-vs-aipref-vocabulary/) Permit - [AI Crawler User-Agent Tokens in robots.txt vs agent-permissions.json](/compare/ai-crawler-tokens-robots-vs-agent-permissions-json/) Permit - [Cloudflare Pay per crawl vs x402](/compare/cloudflare-pay-per-crawl-vs-x402/) Pay - [OAuth Protected Resource and Authorization Server Metadata (as used for agent authorization) vs auth.md](/compare/oauth-metadata-for-agents-vs-auth-md/) Permit - [Agent Authorization Grant vs Identity Assertion JWT Authorization Grant](/compare/aauth-vs-identity-assertion-authz-grant/) Permit - [Agent Audit Trail vs AI Agent Execution Profile of SCITT](/compare/agent-audit-trail-vs-scitt-ai-agent-execution/) Account - [NLWeb vs Model Context Protocol](/compare/nlweb-vs-mcp/) Act - [agents.json vs Agentic Resource Discovery](/compare/agents-json-vs-ard/) Act / Discover - [Agent Readability Spec vs llms.txt](/compare/vercel-agent-readability-vs-llms-txt/) Read - [Agent Client Protocol vs Agent Connect Protocol (AGNTCY)](/compare/agent-client-protocol-vs-agent-connect-protocol/) Act - [Agent Communication Protocol vs Agent Connect Protocol (AGNTCY)](/compare/agent-communication-protocol-vs-agent-connect-protocol/) Coordinate / Act - [Agent Communication Protocol vs Agentic Commerce Protocol](/compare/agent-communication-protocol-vs-agentic-commerce-protocol/) Coordinate / Pay - [Agent Connect Protocol (AGNTCY) vs Agentic Commerce Protocol](/compare/agent-connect-protocol-vs-agentic-commerce-protocol/) Act / Pay - [Cloudflare Pay per crawl vs L402](/compare/cloudflare-pay-per-crawl-vs-l402/) Pay - [Cloudflare Pay per crawl vs Machine Payments Protocol](/compare/cloudflare-pay-per-crawl-vs-mpp/) Pay - [Cloudflare Pay per crawl vs s402](/compare/cloudflare-pay-per-crawl-vs-s402/) Pay - [L402 vs Machine Payments Protocol](/compare/l402-vs-mpp/) Pay - [L402 vs s402](/compare/l402-vs-s402/) Pay - [Machine Payments Protocol vs s402](/compare/mpp-vs-s402/) Pay - [s402 vs x402](/compare/s402-vs-x402/) Pay - [AIPREF Content-Usage Attachment vs AIPREF Vocabulary](/compare/aipref-content-usage-attachment-vs-aipref-vocabulary/) Permit - [HTTP Message Signatures vs Signature Agent Card (Web Bot Auth registry)](/compare/http-message-signatures-vs-web-bot-auth-signature-agent-card/) Identify - [Signature Agent Card (Web Bot Auth registry) vs Web Bot Auth HTTP Message Signatures](/compare/web-bot-auth-signature-agent-card-vs-webbotauth/) Identify Missing a pair? [Ask for it](/submit/), or compare any two over MCP with the compare-protocols prompt.