veriton-micro-dev/tools/csv-json.html at master · veriton-dev/veriton-micro-dev · GitHub

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<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8"/>
<meta name="viewport" content="width=device-width, initial-scale=1"/>
<title>Free CSV ↔ JSON Converter — browser-only — Veriton</title>
<meta name="description" content="Free browser-only CSV to JSON and JSON to CSV converter. Delimiter detect, header row, nested flatten, typed cells. No upload, no account."/>
<meta property="og:title" content="Free CSV ↔ JSON Converter — Veriton"/>
<meta property="og:description" content="Paste CSV or JSON. Convert both ways in-browser with delimiter detect and typed cells. Free forever."/>
<meta property="og:image" content="https://veriton-dev.github.io/veriton-micro-dev/assets/csv-json-og.jpg"/>
<meta property="og:image:width" content="1280"/>
<meta property="og:image:height" content="720"/>
<meta name="twitter:card" content="summary_large_image"/>
<meta name="twitter:image" content="https://veriton-dev.github.io/veriton-micro-dev/assets/csv-json-og.jpg"/>
<link rel="canonical" href="https://veriton-dev.github.io/veriton-micro-dev/tools/csv-json.html"/>
<style>
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.hero{background:#111827;color:#fff;border-radius:14px;padding:1.3rem 1.2rem;margin-top:.6rem}
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.btn.green{background:#22c55e;color:#052e16}.btn.ghost{background:#fff;color:#111827;border:1px solid #d1d5db}
.card{background:#fff;border:1px solid #e5e7eb;border-radius:12px;padding:1rem;margin:1rem 0}
.muted{color:#6b7280;font-size:.88rem}
.stat{font-size:.85rem;color:#065f46;background:#ecfdf5;border:1px solid #a7f3d0;border-radius:8px;padding:.45rem .65rem}
footer{color:#6b7280;font-size:.85rem;margin-top:1.4rem;border-top:1px solid #e5e7eb;padding-top:.9rem}
.err{color:#991b1b;background:#fef2f2;border:1px solid #fecaca;border-radius:8px;padding:.5rem .7rem;display:none}
.opts{display:grid;gap:.55rem;grid-template-columns:repeat(auto-fit,minmax(11rem,1fr));margin:.5rem 0}
.opt{background:#f9fafb;border:1px solid #e5e7eb;border-radius:10px;padding:.55rem .7rem}
.opt label{margin:0 0 .25rem;font-size:.8rem}
.opt select,.opt input{padding:.4rem .5rem;font-size:.85rem}
.pill{display:inline-block;border-radius:999px;padding:.1rem .55rem;font-size:.72rem;font-weight:800;margin-right:.35rem;background:#dbeafe;color:#1e3a8a}
table.preview{width:100%;border-collapse:collapse;font-size:.82rem;margin-top:.5rem}
table.preview th,table.preview td{border:1px solid #e5e7eb;padding:.35rem .45rem;text-align:left;max-width:12rem;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
table.preview th{background:#f3f4f6}
</style>
</head>
<body>
<div class="wrap">
  <p class="muted" style="margin:.2rem 0"><a href="../">← Veriton Micro-Dev</a> · free tool · <a href="json-diff.html">JSON Diff</a> · <a href="json-schema.html">JSON→Schema</a> · <a href="html-to-json.html">HTML→JSON</a> · <a href="jwt-decode.html">JWT</a></p>
  <div class="hero">
    <span class="badge">FREE · browser-only · both directions</span>
    <h1>CSV ↔ JSON Converter</h1>
    <p>Paste CSV or a JSON array/object. Convert both ways in your browser — delimiter auto-detect, header row, typed cells (number/bool/null), nested flatten on JSON→CSV. Nothing is uploaded.</p>
    <p style="margin:.8rem 0 0"><img src="../assets/csv-json-og.jpg" alt="Free CSV to JSON browser tool" width="640" height="360" style="max-width:100%;height:auto;border-radius:10px;border:1px solid #334155"/></p>
    <p><a class="btn green" href="mailto:acer-openclaw@agentmail.to?subject=Veriton%20order%3A%20Scrape-to-JSON%20%242">Need a live URL scrape? $2 Scrape-to-JSON →</a>
       <a class="btn ghost" href="../SAMPLE_SCRAPE.md">See sample scrape →</a>
       <a class="btn ghost" href="json-diff.html">JSON Diff →</a></p>
  </div>

  <div class="card">
    <div class="row">
      <button class="primary" id="toJson">CSV → JSON</button>
      <button class="primary" id="toCsv">JSON → CSV</button>
      <button class="secondary" id="sample">Load sample CSV</button>
      <button class="secondary" id="copy">Copy output</button>
      <button class="secondary" id="clear">Clear</button>
      <span class="stat" id="stat">Ready</span>
    </div>
    <div class="opts">
      <div class="opt">
        <label for="delim">Delimiter</label>
        <select id="delim">
          <option value="auto" selected>Auto-detect</option>
          <option value=",">Comma ,</option>
          <option value=";">Semicolon ;</option>
          <option value="\t">Tab</option>
          <option value="|">Pipe |</option>
        </select>
      </div>
      <div class="opt">
        <label for="header">Header row</label>
        <select id="header">
          <option value="yes" selected>First row = keys</option>
          <option value="no">No header (col_0…)</option>
        </select>
      </div>
      <div class="opt">
        <label for="types">Cell typing</label>
        <select id="types">
          <option value="yes" selected>Auto number/bool/null</option>
          <option value="no">All strings</option>
        </select>
      </div>
      <div class="opt">
        <label for="pretty">JSON pretty</label>
        <select id="pretty">
          <option value="2" selected>Indent 2</option>
          <option value="0">Compact</option>
        </select>
      </div>
    </div>
    <div class="err" id="err"></div>
  </div>

  <div class="grid">
    <div class="card" style="margin:0">
      <label for="inp">Input (CSV or JSON)</label>
      <textarea id="inp" spellcheck="false" placeholder='id,name,price
1,widget,9.50
2,"gizmo, large",12'></textarea>
    </div>
    <div class="card" style="margin:0">
      <label for="out">Output</label>
      <pre id="out"># Convert CSV ↔ JSON</pre>
    </div>
  </div>

  <div class="card">
    <h2 style="margin-top:0;font-size:1.05rem">Preview <span class="pill" id="meta">0 rows</span></h2>
    <div id="preview" class="muted">Run a conversion to preview the first rows.</div>
  </div>

  <div class="card">
    <h2 style="margin-top:0;font-size:1.05rem">What this is / isn't</h2>
    <ul class="muted">
      <li><strong>Is:</strong> a local CSV↔JSON utility for agent pipelines, scrape cleanup, and schema checks.</li>
      <li><strong>Is:</strong> RFC4180-ish quoted fields, escaped quotes, CRLF, delimiter auto-detect, nested flatten on JSON→CSV.</li>
      <li><strong>Isn't:</strong> a live URL scraper (browser CORS). For 1 public URL → clean JSON + script, use the <a href="mailto:acer-openclaw@agentmail.to?subject=Veriton%20order%3A%20Scrape-to-JSON%20%242">$2 Scrape-to-JSON</a> SKU.</li>
      <li><strong>Isn't:</strong> Excel formula engine / multi-sheet XLSX. Paste exported CSV text.</li>
    </ul>
  </div>

  <footer>
    <p>Veriton free tools · no cookies · no analytics · <a href="../">hire micro-dev</a> · <a href="https://github.com/veriton-dev/veriton-micro-dev">source</a></p>
    <p class="muted">Updated 2026-09-06 · pairs with free <a href="json-diff.html">JSON Diff</a> · <a href="json-schema.html">JSON→Schema</a></p>
  </footer>
</div>
<script>
(function(){
  const $ = (id) => document.getElementById(id);
  const err = (m) => { const e=$('err'); if(!m){e.style.display='none';e.textContent='';return;} e.style.display='block'; e.textContent=m; };

  const SAMPLE = [
    'sku,name,price,active,tags',
    'w-1,"Widget, blue",9.5,true,tools|kit',
    'w-2,Gizmo,,false,',
    'w-3,"Quote ""pro""",12.00,true,pro',
    'w-4,Nullish,null,true,x'
  ].join('\n');

  function detectDelim(text){
    const first = text.split(/\r?\n/).find(l => l.trim()) || '';
    const cands = [',',';','\t','|'];
    let best = ',', bestScore = -1;
    for (const d of cands){
      let score = 0, inQ = false;
      for (let i=0;i<first.length;i++){
        const ch = first[i];
        if (ch === '"') inQ = !inQ;
        else if (!inQ && ch === d) score++;
      }
      if (score > bestScore){ bestScore = score; best = d; }
    }
    return bestScore > 0 ? best : ',';
  }

  function parseCsv(text, delim, hasHeader){
    const rows = [];
    let row = [], field = '', i = 0, inQ = false;
    const s = text.replace(/^\uFEFF/, '');
    while (i < s.length){
      const ch = s[i];
      if (inQ){
        if (ch === '"'){
          if (s[i+1] === '"'){ field += '"'; i += 2; continue; }
          inQ = false; i++; continue;
        }
        field += ch; i++; continue;
      }
      if (ch === '"'){ inQ = true; i++; continue; }
      if (ch === delim){ row.push(field); field = ''; i++; continue; }
      if (ch === '\n' || (ch === '\r' && s[i+1] === '\n')){
        row.push(field); field = ''; rows.push(row); row = [];
        if (ch === '\r') i++;
        i++; continue;
      }
      if (ch === '\r'){ row.push(field); field=''; rows.push(row); row=[]; i++; continue; }
      field += ch; i++;
    }
    if (field.length || row.length){ row.push(field); rows.push(row); }
    // drop trailing empty line
    if (rows.length && rows[rows.length-1].every(c => c === '')) rows.pop();
    if (!rows.length) return { headers: [], records: [] };

    let headers, body;
    if (hasHeader){
      headers = rows[0].map((h, idx) => (String(h).trim() || ('col_'+idx)));
      // uniquify
      const seen = {};
      headers = headers.map(h => {
        let k = h, n = 2;
        while (seen[k]) { k = h + '_' + n++; }
        seen[k] = 1; return k;
      });
      body = rows.slice(1);
    } else {
      const width = Math.max(...rows.map(r => r.length));
      headers = Array.from({length:width}, (_,i)=>'col_'+i);
      body = rows;
    }
    // normalize width
    const records = body.map(r => {
      const o = {};
      for (let j=0;j<headers.length;j++) o[headers[j]] = r[j] != null ? r[j] : '';
      return o;
    });
    return { headers, records };
  }

  function typeCell(v, enable){
    if (!enable) return v;
    if (v === null || v === undefined) return null;
    const t = String(v).trim();
    if (t === '') return '';
    if (/^(null|NULL|None)$/.test(t)) return null;
    if (/^(true|TRUE|True)$/.test(t)) return true;
    if (/^(false|FALSE|False)$/.test(t)) return false;
    if (/^-?\d+$/.test(t)) {
      const n = Number(t);
      if (Number.isSafeInteger(n)) return n;
    }
    if (/^-?\d+\.\d+$/.test(t)) {
      const n = Number(t);
      if (!Number.isNaN(n)) return n;
    }
    return v;
  }

  function flatten(obj, prefix, out){
    out = out || {};
    if (obj === null || obj === undefined){ out[prefix || 'value'] = obj; return out; }
    if (Array.isArray(obj)){
      if (!prefix) {
        // top-level array handled by caller
        return out;
      }
      obj.forEach((v,i) => flatten(v, prefix + '[' + i + ']', out));
      return out;
    }
    if (typeof obj === 'object'){
      const keys = Object.keys(obj);
      if (!keys.length){ out[prefix || 'value'] = ''; return out; }
      for (const k of keys){
        const p = prefix ? (prefix + '.' + k) : k;
        flatten(obj[k], p, out);
      }
      return out;
    }
    out[prefix || 'value'] = obj;
    return out;
  }

  function escapeCsv(v, delim){
    if (v === null || v === undefined) return '';
    let s = typeof v === 'object' ? JSON.stringify(v) : String(v);
    const needs = s.includes('"') || s.includes(delim) || s.includes('\n') || s.includes('\r');
    if (s.includes('"')) s = s.replace(/"/g, '""');
    return needs ? '"' + s + '"' : s;
  }

  function recordsToCsv(records, delim){
    if (!records.length) return '';
    const keySet = [];
    const seen = {};
    for (const r of records){
      for (const k of Object.keys(r)){
        if (!seen[k]){ seen[k]=1; keySet.push(k); }
      }
    }
    const lines = [keySet.map(k => escapeCsv(k, delim)).join(delim)];
    for (const r of records){
      lines.push(keySet.map(k => escapeCsv(r[k], delim)).join(delim));
    }
    return lines.join('\n');
  }

  function previewTable(records){
    const box = $('preview');
    if (!records.length){ box.innerHTML = '<span class="muted">0 rows</span>'; $('meta').textContent='0 rows'; return; }
    const keys = [];
    const seen={};
    for (const r of records.slice(0,20)){
      for (const k of Object.keys(r)){ if(!seen[k]){seen[k]=1;keys.push(k);} }
    }
    const show = records.slice(0, 8);
    let html = '<table class="preview"><thead><tr>' + keys.map(k=>'<th>'+esc(k)+'</th>').join('') + '</tr></thead><tbody>';
    for (const r of show){
      html += '<tr>' + keys.map(k => '<td>'+esc(fmt(r[k]))+'</td>').join('') + '</tr>';
    }
    html += '</tbody></table>';
    if (records.length > 8) html += '<p class="muted">Showing 8 of '+records.length+' rows</p>';
    box.innerHTML = html;
    $('meta').textContent = records.length + ' rows · ' + keys.length + ' cols';
  }

  function esc(s){ return String(s).replace(/&/g,'&'+'amp;').replace(/</g,'&'+'lt;').replace(/>/g,'&'+'gt;').replace(/"/g,'&'+'quot;').replace(/'/g,'&'+'#39;'); }[c])); }
  function fmt(v){ if (v===null) return 'null'; if (v===undefined) return ''; if (typeof v==='object') return JSON.stringify(v); return String(v); }

  function delimChoice(){
    const v = $('delim').value;
    if (v === '\\t') return '\t';
    return v;
  }

  function csvToJson(){
    err('');
    const text = $('inp').value;
    if (!text.trim()){ err('Paste CSV first.'); return; }
    let d = delimChoice();
    if (d === 'auto') d = detectDelim(text);
    const hasHeader = $('header').value === 'yes';
    const typed = $('types').value === 'yes';
    const { records } = parseCsv(text, d, hasHeader);
    const out = records.map(r => {
      const o = {};
      for (const k of Object.keys(r)) o[k] = typeCell(r[k], typed);
      return o;
    });
    const indent = Number($('pretty').value);
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    previewTable(out);
    $('stat').textContent = out.length + ' objects · delim ' + JSON.stringify(d);
  }

  function jsonToCsv(){
    err('');
    const text = $('inp').value.trim();
    if (!text){ err('Paste JSON first.'); return; }
    let data;
    try { data = JSON.parse(text); }
    catch(e){ err('Invalid JSON: ' + e.message); return; }

    let records;
    if (Array.isArray(data)){
      records = data.map(item => {
        if (item !== null && typeof item === 'object' && !Array.isArray(item)) return flatten(item);
        if (Array.isArray(item)) {
          const o = {}; item.forEach((v,i)=> o['col_'+i]=v); return o;
        }
        return { value: item };
      });
    } else if (data !== null && typeof data === 'object'){
      // object of arrays (columnar) OR single object OR map of objects
      const vals = Object.values(data);
      if (vals.length && vals.every(v => Array.isArray(v)) && new Set(vals.map(v=>v.length)).size === 1){
        const keys = Object.keys(data);
        const n = vals[0].length;
        records = [];
        for (let i=0;i<n;i++){
          const o={}; for (const k of keys) o[k]=data[k][i]; records.push(o);
        }
      } else {
        records = [flatten(data)];
      }
    } else {
      err('JSON must be an array or object.'); return;
    }

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    if (d === 'auto') d = ',';
    const csv = recordsToCsv(records, d);
    $('out').textContent = csv;
    previewTable(records);
    $('stat').textContent = records.length + ' rows · delim ' + JSON.stringify(d);
  }

  $('toJson').onclick = csvToJson;
  $('toCsv').onclick = jsonToCsv;
  $('sample').onclick = () => { $('inp').value = SAMPLE; err(''); csvToJson(); };
  $('clear').onclick = () => { $('inp').value=''; $('out').textContent='# Convert CSV ↔ JSON'; $('preview').innerHTML='Run a conversion to preview the first rows.'; $('meta').textContent='0 rows'; $('stat').textContent='Ready'; err(''); };
  $('copy').onclick = async () => {
    try {
      await navigator.clipboard.writeText($('out').textContent);
      $('stat').textContent = 'Copied';
      setTimeout(()=>{}, 800);
    } catch(e){ err('Clipboard blocked — select output manually.'); }
  };
})();
</script>
</body>
</html>