Paytools vs MCP Replay

Paytools is an offline payment-engineering workbench for developers, QA engineers, integrators, students, and fintech teams. Decode and inspect common payment-message structures, explore field definitions, convert technical data, and keep essential payment references close at hand. Processing happens locally on your device, so pasted messages and imported files are not uploaded to a server. PAYMENT TOOLS • Inspect ISO 8583 MTIs, bitmaps, and present data elements • Decode and build primary and secondary bitmaps • Parse BER-TLV data and identify common EMV tags • Recognize SWIFT MT blocks and ISO 20022 XML messages • Convert between HEX, ASCII, decimal, binary, and packed BCD • Validate synthetic card numbers with the Luhn algorithm • Compose synthetic Track 2 and ISO-0 PIN-block test data • Use development utilities for XOR and DES odd parity KNOWLEDGE LIBRARY • Search all 128 ISO 8583 data elements • Learn ISO 8583:1987, 1993, and 2003 MTI concepts • Follow authorization from merchant to acquirer, scheme, and issuer • Understand STIP, advice, reversal, clearing, and settlement flows • Review ISO 20022 message families and validation concepts • Study EMV transaction and cryptogram terminology CODES AND FIELDS Search operational response-code references for common ISO profiles, Visa, Mastercard, UnionPay/UPI, 3-D Secure, and gateway HTTP outcomes. Open any ISO field for its purpose, format, and implementation notes, including an expanded guide to DE22 POS Entry Mode. PRIVATE BY DESIGN Paytools has no account requirement and no cloud processing. Use synthetic or appropriately masked test data. Production payment formats and code meanings can vary by network, region, product, and specification release. Paytools is an independent educational and development utility. It is not affiliated with or endorsed by any payment network. Formal certification and production processing require the current authorized specifications, test packs, approved cryptographic systems, and applicable security controls.

MCP Replay is a trace viewer for the Model Context Protocol, the open standard AI agents use to call tools. Record a session with the free mcp-tape command line tool, then open it on your phone: every request, response, error, and latency, organized and searchable. WHAT YOU CAN DO - Open .jsonl traces from Files, AirDrop, or any share sheet - Follow a replay link someone sent you, or paste a bare share ID - Watch a live session streaming from mcp-tape on your own network - See paired tool calls with latencies, and per-tool stats (count, errors, avg, p95) - Filter the timeline by tool or method - Share a trace as a link that expires after 30 days, with a delete token so you stay in control BUILT FOR PRIVACY Traces stay on your phone. Nothing is uploaded unless you explicitly share a trace, and there are no accounts, no analytics, and no tracking. Live mode connects directly to your own computer; the stream never touches a server. FOR ANYONE BUILDING WITH AGENTS If you use Claude, ChatGPT, or any MCP-compatible agent framework and have ever asked "what did it actually do?", this is the answer. Record with one command: npx mcp-tape -- your-mcp-server-command Then open the trace here or at mcpreplay.dev. MCP Replay is open source and independent. It works with any tool that emits the open mcp-tape trace format.