About ViewJSON

ViewJSON is a free online JSON viewer and formatter built for developers who work with APIs that return Base64-encoded media. Unlike traditional JSON formatters that treat every string value as plain text, ViewJSON automatically detects Base64-encoded content and renders it as actual images, audio players, video players, or PDF previews — directly inside the JSON structure.

It supports over 15 media formats including PNG, JPEG, WebP, MP3, WAV, MP4, and PDF. Detection works by decoding just the first 64 bytes of each string and matching against known file format signatures (magic numbers), so even a 100MB Base64 string is identified in under a millisecond.

The editor also handles malformed input gracefully — trailing commas, comments, and unquoted keys are silently fixed before parsing. If you work with JSONL (newline-delimited JSON), each line is parsed independently so a single bad record won't block the rest.

Everything runs locally in your browser. Your data is never uploaded to any server — not for processing, not for analytics, not for anything.

We spend our days building wrappers for multimodal AI APIs — OCR, text-to-speech, speech-to-text, vision models like GPT-4o and Qwen-VL, image generation. Basically everything that takes or returns Base64.

"We were testing a text-to-speech pipeline that generates audio in multiple voices. Each response contained 4–6 Base64 audio clips. Our workflow was: find the string, copy it, open an online decoder, paste, hit play. Repeat for the next voice. Across a dozen prompt variations, that's roughly 60 round-trips to a decoder."

The input side was just as painful. We were testing a batch OCR pipeline that returned 47 cropped images in one JSON response — 47 Base64 strings that we had to decode one by one just to check if the crops looked right. When a prompt variation produced bad results, there was no quick way to tell which images were off.

We started asking — what would it take to auto-detect which strings are media and render them inline? That question led to ViewJSON: a tool where you paste your JSON and immediately see every image, hear every audio clip, and watch every video, without leaving the page.