Developer & AI tools

Utilities for developers and AI builders: JSON repair, JWT decoding, cron parsing, function-calling schema conversion and more.

LLM JSON Repair Fix broken JSON produced by LLMs: trailing commas, single quotes, unquoted keys, markdown fences and truncated output. Free, private, runs in your browser. OpenAPI to Function Calling Convert an OpenAPI 3 spec (JSON or YAML) into OpenAI function-calling tools or Anthropic tool-use schemas. Free, private, browser-based. CSV to JSONL Converter Turn CSV rows into JSONL training data for fine-tuning. Map columns to prompt/completion or chat messages, with sample data. Free and private. JWT Decoder Decode JWT header and payload instantly, inspect claims, and check exp/iat/nbf validity times. Free, private, runs entirely in your browser. Cron Expression Parser Translate a 5-field cron expression into plain English and preview the next 5 run times. Free, private, browser-based crontab explainer. Unix Timestamp Converter Convert Unix timestamps to human dates and back, with millisecond support and multiple timezones. Free, private, browser-based. Base64 Encoder & Decoder Encode and decode Base64 text or files, with URL-safe alphabet toggle and full UTF-8 support. Free, private, runs in your browser. Password Generator Generate strong random passwords with crypto-grade randomness. Choose length, character sets, and batch counts. Free, private, offline. UUID Generator Generate random v4 and time-ordered v7 UUIDs in bulk, with uppercase and hyphen options. Free, private, runs in your browser. Webhook Signature Validator Validate webhook signatures locally: Meta, Shopify, Stripe and Slack HMAC-SHA256 presets with your secret and payload. Free, private, browser-based. API Key Identifier Identify any API key's provider and type from 15+ known formats — OpenAI, GitHub, AWS, Stripe, Slack — plus leak response steps. Runs in your browser. PEM Certificate Decoder Decode PEM certificates, CSRs and public keys in your browser: subject, issuer, SANs, validity and expiry countdown. Free, private X.509 parser. APNs JWT Generator Generate an APNs provider token from your .p8 key, Key ID, Team ID and bundle ID. ES256 signing runs locally in your browser — keys are never uploaded. Provisioning Profile Parser Parse iOS .mobileprovision files in your browser: expiry countdown, entitlements, certificate and device counts. No upload — 100% local parsing. Webhook Replay Builder Build a signed webhook replay request: paste a payload and secret, get the Meta, Shopify or Stripe signature header plus a ready-to-paste curl command. Service Account JWT Debugger Parse a Google service account JSON key (redacted), generate RS256-signed JWT grants for OAuth scopes and decode existing tokens — all locally in your browser. Meta App Secret Proof Compute the appsecret_proof HMAC-SHA256 for Meta Graph API calls from your access token and app secret, with example URL and curl. Fully client-side.