{"opensite":"0.1","url":"https://jsonl.co/","canonical":"https://jsonl.co/","site":{"name":"jsonl.co","web":"https://jsonl.co"},"kind":"product","title":"jsonl.co","description":"Use this JSONL viewer to open, search, and edit JSONL (JSON Lines/NDJSON) files up to 1GB in your browser. Free, private, no uploads — with validation and tools.","image":{"url":"https://jsonl.co/og?title=JSONL%20Viewer%20%26%20Editor%20Online%20%E2%80%94%20Open%20Large%20JSONL%20Files%20(No%20Upload)"},"language":"en","tags":["developer"],"feeds":[],"published_at":null,"modified_at":null,"fetched_at":"2026-11-09T11:36:50.125Z","status":"live","source":"read","cards":{"og":{"title":"JSONL Viewer & Editor Online — Open Large JSONL Files (No Upload)","description":"Use this JSONL viewer to open, search, and edit JSONL (JSON Lines/NDJSON) files up to 1GB in your browser. Free, private, no uploads — with validation and tools.","url":"https://jsonl.co","site_name":"jsonl.co","locale":"en_US","image:alt":"JSONL Viewer & Editor Online — Open Large JSONL Files (No Upload)","image":"https://jsonl.co/og?title=JSONL%20Viewer%20%26%20Editor%20Online%20%E2%80%94%20Open%20Large%20JSONL%20Files%20(No%20Upload)","locale:alternate":"zh_CN","type":"website"},"twitter":{"card":"summary_large_image","title":"JSONL Viewer & Editor Online — Open Large JSONL Files (No Upload)","description":"Use this JSONL viewer to open, search, and edit JSONL (JSON Lines/NDJSON) files up to 1GB in your browser. Free, private, no uploads — with validation and tools.","image":"https://jsonl.co/og?title=JSONL%20Viewer%20%26%20Editor%20Online%20%E2%80%94%20Open%20Large%20JSONL%20Files%20(No%20Upload)"}},"jsonld":[{"@context":"https://schema.org","@type":"WebSite","name":"jsonl.co","url":"https://jsonl.co","description":"Open and edit JSONL files up to 1GB instantly in your browser. Free online JSONL viewer with streaming, syntax highlighting, and format conversion. No sign-up, no upload — 100% private.","publisher":{"@type":"Organization","name":"jsonl.co"}},{"@context":"https://schema.org","@type":"FAQPage","mainEntity":[{"@type":"Question","name":"How large of a JSONL file can I open?","acceptedAnswer":{"@type":"Answer","text":"jsonl.co can handle JSONL files up to 1GB and beyond. We use streaming technology to read your file in chunks, so it loads instantly without consuming all your memory. Only the visible portion is rendered at any time."}},{"@type":"Question","name":"Is my data sent to any server?","acceptedAnswer":{"@type":"Answer","text":"No. All processing happens 100% locally in your browser. Your JSONL data never leaves your device — no uploads, no server-side processing. This makes jsonl.co safe for sensitive and proprietary data."}},{"@type":"Question","name":"What is JSONL format?","acceptedAnswer":{"@type":"Answer","text":"JSONL (JSON Lines) is a text format where each line is a valid JSON object, separated by newlines. It’s widely used for streaming data, log files, and machine learning datasets. Unlike JSON arrays, JSONL files can be processed line by line without loading the entire file into memory. Read our full guide on JSONL format →"}},{"@type":"Question","name":"What’s the difference between JSON and JSONL?","acceptedAnswer":{"@type":"Answer","text":"JSON stores data as a single object or array, while JSONL stores one JSON object per line. JSONL is better for large datasets and streaming because each line can be parsed independently. See the detailed JSON vs JSONL comparison →"}},{"@type":"Question","name":"What file formats are supported?","acceptedAnswer":{"@type":"Answer","text":"jsonl.co supports .jsonl, .ndjson (Newline Delimited JSON), .json, and .txt files. All formats are parsed line by line as JSONL content."}},{"@type":"Question","name":"Can I edit JSONL files?","acceptedAnswer":{"@type":"Answer","text":"Yes. For smaller files, you can directly edit the raw JSONL text in the left panel. Changes are parsed and validated in real time on the right panel. You can also add new lines, delete lines, and use find & replace. When you’re done, export the edited file with one click."}},{"@type":"Question","name":"Can I use jsonl.co as an NDJSON viewer?","acceptedAnswer":{"@type":"Answer","text":"Yes. jsonl.co fully supports NDJSON (Newline Delimited JSON), which follows the same one-object-per-line format as JSONL. Simply open your .ndjson file and it will be parsed and displayed just like any JSONL file."}},{"@type":"Question","name":"Can I view OpenAI fine-tuning JSONL files?","acceptedAnswer":{"@type":"Answer","text":"Yes. jsonl.co is ideal for viewing and editing OpenAI fine-tuning datasets in JSONL format. You can inspect prompt-completion pairs, validate each line's structure, and export corrected files — all without uploading your training data to any server."}}]},{"@context":"https://schema.org","@type":"SoftwareApplication","name":"JSONL Viewer & Editor Online","applicationCategory":"DeveloperApplication","operatingSystem":"Web","offers":{"@type":"Offer","price":"0","priceCurrency":"USD"},"description":"Open and edit JSONL files up to 1GB instantly in your browser. Free online JSONL viewer with streaming, syntax highlighting, and format conversion. No sign-up, no upload — 100% private.","url":"https://jsonl.co/","author":{"@type":"Organization","name":"jsonl.co","url":"https://jsonl.co","founder":{"@type":"Person","name":"Jerry Fan","url":"https://jsonl.co/about#author","image":"https://jsonl.co/images/author.svg"}},"featureList":["Stream and view JSONL files up to 1GB+","100% browser-based, no upload required","Side-by-side raw and parsed view","JSONL, NDJSON, JSON format support","Convert between JSONL, JSON, and CSV","Syntax highlighting and real-time validation","Built-in JSONL validator with line-by-line error detection","View OpenAI fine-tuning and Hugging Face datasets"],"browserRequirements":"Requires a modern browser with JavaScript enabled"}]}