Local-first developer converters
Private developer format converters.
Convert JSON, CSV, YAML, XML, encoding, and timestamps entirely in your browser. No uploads, accounts, or waiting for a server.
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Popular tools
High-frequency tools for data conversion and account migration, ordered by practical demand.
Account & Session
ChatGPT Session Converter
Convert ChatGPT session JSON into sub2api, CPA, Cockpit, 9router, AxonHub or Codex-Manager formats locally.
Account & Session
Card Key to Sub2API Converter
Convert card keys (email----pwd----token) into Sub2API import JSON, token lists or CPA format locally.
Data
JSON ↔ CSV
Convert JSON to CSV or CSV to JSON instantly in your browser. Handles headers, quotes, commas and multiline values without uploads.
Encoding
Text ↔ Base64
Encode UTF-8 text to Base64 or decode Base64 back to text locally in your browser. Free, instant, emoji-safe and no server uploads.
Data
JSON ↔ YAML
Convert JSON to YAML or YAML to JSON on one private browser page. Supports nested objects and arrays without uploads.
Data
JSON ↔ XML
Convert JSON to XML or XML to JSON locally. Supports attributes, text and repeated elements while rejecting unsafe entity declarations.
Time
Unix Timestamp ↔ DateTime
Convert Unix timestamps in seconds or milliseconds to UTC ISO 8601 dates, or convert ISO DateTime back to Unix seconds locally and instantly.
Complete index
All tools
Account & Session
Data
Encoding
Time
Type Generators
Guides
Deeper reading
Guide
JSON vs CSV
When spreadsheets win, when nested data matters, and how to avoid lossy exports.
Guide
Base64 vs Encryption
A plain-language guide to transport encoding, real secrecy, and where each belongs.
Guide
SEO Growth and Monetization
What strong tool sites do well, what to copy, and how to turn traffic into durable revenue.