Free tools that respect your privacy

Every tool on ToolAcorn runs entirely in your browser. Press a button, get a result — nothing is ever uploaded.

Developer & AI

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.

Media & Images

Fast client-side image tools: compress, resize, convert to WebP, strip EXIF, build favicons and QR codes.

Image Compressor Compress JPG, PNG and WebP images with a quality slider and batch support. See savings before you download. Free, private, browser-based. Image Resizer Resize images by exact pixels or percentage, with aspect-ratio lock and batch processing. Free, private, browser-based. Convert to WebP Convert JPG and PNG images to WebP with adjustable quality and batch support. Free, private, runs entirely in your browser. Favicon Generator Upload one image and get every favicon size you need — 16, 32, 180, 192, 512 — packed in a zip. Free, private, browser-based. QR Code Generator Create QR codes for text, URLs, WiFi networks and contact cards, with size and error-correction controls. Free, private, browser-based. EXIF Remover Remove EXIF metadata — GPS location, camera, timestamps — from JPG images before sharing. Free, private, browser-based. OG Image Generator Design 1200×630 Open Graph social cards in your browser: title, brand colors, gradient, badge. Export PNG free, no upload, no watermark. Image to Base64 Convert images to Base64 data URIs locally, with CSS, HTML and JSON output formats and size warnings. Free, private — no upload. Color Palette Extractor Extract a dominant color palette from any image in your browser. Click-to-copy hex with RGB and HSL values. Free, private, no upload.

Calculators

Practical calculators for LLM context windows, API costs, VRAM estimates and home mortgages.

Context Window Calculator Convert between tokens, English words and book pages, with presets for GPT, Claude and Gemini context windows. Free, browser-based. LLM API Cost Calculator Estimate monthly LLM API spend: pick a model, enter input/output tokens and request volume. Prices for GPT, Claude, Gemini. Free, private. LLM VRAM Calculator Estimate GPU VRAM for running an LLM: parameters × quantization (FP16/INT8/Q4/Q2) plus context KV cache. Free, browser-based. Mortgage Calculator Calculate monthly mortgage payments, total interest and amortization from loan amount, rate and term, with a balance chart. Free, private. Date Duration Calculator Calculate the duration between two dates in days, weeks, months and working days. Free browser-based date difference calculator. Aspect Ratio Calculator Calculate new dimensions by aspect ratio: 16:9, 4:3, 1:1, 9:16, 21:9 presets with width or height lock. Free, instant, browser-based.

Text & Files

Clean transcripts, shift subtitles, count words, merge and split PDFs, and cut large CSV files down to size.

Transcript Cleaner Clean transcripts automatically: strip um/uh filler words, merge broken lines, fix casing, optional sentence paragraphs. Free, private. SRT Subtitle Tools Shift SRT timing by seconds, scale timestamps, and convert between SRT and VTT formats. Free, private, browser-based subtitle toolkit. Word Counter Count words, characters, sentences and paragraphs with reading-time estimates as you type. Free, private, browser-based. PDF Merger Merge multiple PDFs into one: drag files in, reorder, and download a combined PDF. Free, private — files never leave your browser. PDF Splitter Split a PDF by page ranges or extract selected pages into new PDFs. Free, private — processing stays in your browser. CSV Splitter Split large CSV files into chunks by row count, or extract selected columns. Download as separate files or a zip. Free, private. Text Diff Checker Compare two texts line by line with added, removed and changed lines highlighted. Free diff checker that runs entirely in your browser. Case Converter Convert text to UPPERCASE, lowercase, Title Case, camelCase, PascalCase, snake_case, kebab-case and URL slugs at once. Free, private. CSV ↔ JSON Converter Convert CSV to JSON and JSON to CSV in your browser: custom delimiters, header toggle, type inference. Free, private, RFC 4180 parser.