diff --git a/ui/components/ConditionForm.vue b/ui/components/ConditionForm.vue
index 49afd01e..a39dbc3c 100644
--- a/ui/components/ConditionForm.vue
+++ b/ui/components/ConditionForm.vue
@@ -71,6 +71,11 @@
                   <label class="label is-inline" for="filter">
                     <span class="icon"><i class="fa-solid fa-filter" /></span>
                     Condition Filter
+                    <template v-if="!addInProgress || form.filter">
+                      - <NuxtLink @click="test_data.show = true" class="is-bold">
+                        Test filter logic
+                      </NuxtLink>
+                    </template>
                   </label>
                   <div class="control">
                     <input type="text" class="input" id="filter" v-model="form.filter" :disabled="addInProgress"
@@ -78,13 +83,7 @@
                   </div>
                   <span class="help">
                     <span class="icon"><i class="fa-solid fa-info" /></span>
-                    <span>
-                      The yt-dlp <code>[--match-filters]</code> filter logic.
-                      <NuxtLink @click="test_data.show = true" :disabled="addInProgress || !form.filter"
-                        class="is-bold">
-                        Test filter logic
-                      </NuxtLink>
-                    </span>
+                    <span>yt-dlp <code>[--match-filters]</code> logic.</span>
                   </span>
                 </div>
               </div>
diff --git a/ui/utils/ytdlp.ts b/ui/utils/ytdlp.ts
new file mode 100644
index 00000000..efbb7ac5
--- /dev/null
+++ b/ui/utils/ytdlp.ts
@@ -0,0 +1,107 @@
+const NUMBER_RE = /\d+(?:\.\d+)?/;
+
+function match_str(filterStr: string, dct: Record<string, any>, incomplete: boolean | Set<string> = false): boolean {
+  return filterStr
+    .split(/(?<!\\)&/)
+    .every(filterPart => _match_one(filterPart.replace(/\\&/g, '&'), dct, incomplete));
+}
+
+function lookup_unit_table(unitTable: Record<string, number>, s: string, strict = false): number | null {
+  const numRe = strict ? NUMBER_RE : /\d+[,.]?\d*/;
+  const unitsRe = Object.keys(unitTable).map(u => u.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')).join('|');
+  const re = new RegExp(`^(?<num>${numRe.source})\s*(?<unit>${unitsRe})\b`, strict ? '' : 'i');
+
+  const m = s.match(re);
+  if (!m || !m.groups) return null;
+
+  const num = parseFloat(m.groups.num.replace(',', '.'));
+  const mult = unitTable[m.groups.unit];
+
+  return Math.round(num * mult);
+}
+
+function parse_filesize(s: string | null): number | null {
+  if (!s) return null;
+
+  const UNIT_TABLE: Record<string, number> = {
+    B: 1, bytes: 1, b: 1,
+    KiB: 1024, KB: 1000, kB: 1024, kb: 1000, kilobytes: 1000, kibibytes: 1024,
+    MiB: 1024 ** 2, MB: 1000 ** 2, megabytes: 1000 ** 2, mebibytes: 1024 ** 2,
+    GiB: 1024 ** 3, GB: 1000 ** 3, gigabytes: 1000 ** 3, gibibytes: 1024 ** 3,
+    TiB: 1024 ** 4, TB: 1000 ** 4, terabytes: 1000 ** 4, tebibytes: 1024 ** 4,
+  };
+
+  return lookup_unit_table(UNIT_TABLE, s);
+}
+
+function parse_duration(s: string): number | null {
+  if (!s.trim()) return null;
+
+  const durationRe = /^(?:(?:(?<days>\d+):)?(?<hours>\d+):)?(?<mins>\d+):(?<secs>\d{1,2})(?<ms>[.:]\d+)?Z?$/;
+  const m = s.match(durationRe);
+  if (!m || !m.groups) return null;
+
+  const { days, hours, mins, secs, ms } = m.groups;
+
+  return (
+    (parseFloat(days || '0') * 86400) +
+    (parseFloat(hours || '0') * 3600) +
+    (parseFloat(mins || '0') * 60) +
+    parseFloat(secs || '0') +
+    parseFloat((ms || '0').replace(':', '.'))
+  );
+}
+
+function _match_one(filterPart: string, dct: Record<string, any>, incomplete: boolean | Set<string>): boolean {
+  const STRING_OPERATORS: Record<string, Function> = {
+    '*=': (a: string, v: string) => a.includes(v),
+    '^=': (a: string, v: string) => a.startsWith(v),
+    '$=': (a: string, v: string) => a.endsWith(v),
+    '~=': (a: string, v: string) => new RegExp(v).test(a),
+  };
+
+  const COMPARISON_OPERATORS: Record<string, Function> = {
+    ...STRING_OPERATORS,
+    '<=': (a: any, b: any) => a <= b,
+    '<': (a: any, b: any) => a < b,
+    '>=': (a: any, b: any) => a >= b,
+    '>': (a: any, b: any) => a > b,
+    '=': (a: any, b: any) => a == b,
+  };
+
+  const match = filterPart.trim().match(/^([a-z_]+)\s*(!)?\s*([*^$~=<>]+)\s*(?:"(.+)"|'(.+)'|(.+))$/);
+
+  if (match) {
+    const [, key, negation, op, qstr, sstr, ustr] = match;
+    const value = qstr || sstr || ustr;
+    const actual = dct[key];
+
+    const compValue = parse_filesize(value) || parse_duration(value) || value;
+
+    const _cmp = COMPARISON_OPERATORS[op];
+    if (actual === undefined) return incomplete === true || (incomplete instanceof Set && incomplete.has(key));
+
+    return negation ? !_cmp(actual, compValue) : _cmp(actual, compValue);
+  }
+
+  const UNARY_OPERATORS: Record<string, Function> = {
+    '': (v: any) => v != null,
+    '!': (v: any) => v == null,
+  };
+
+  const unaryMatch = filterPart.trim().match(/^(!)?([a-z_]+)$/);
+
+  if (unaryMatch) {
+    const [, op, key] = unaryMatch;
+    const actual = dct[key];
+
+    if (actual === undefined && (incomplete === true || (incomplete instanceof Set && incomplete.has(key)))) return true;
+
+    return UNARY_OPERATORS[op || ''](actual);
+  }
+
+  throw new Error(`Invalid filter part '${filterPart}'`);
+}
+
+
+export { match_str, lookup_unit_table, parse_filesize, parse_duration, _match_one }