Parquet Lens

a fast viewer for parquet, avro, tfrecord, arrow ipc and feather v2 datasets of any size. open a .parquet, .avro, .tfrecord, .arrow, .arrows, .ipc or .feather file and read it as a table. the schema and row count of a parquet file come from its footer, read in 8 ms on a 5,000,000-row, 101 MB file; rows decode as you scroll to them and search streams the whole file. the viewer is free for every format. pro, a one-time purchase, adds whole-file filter queries, export, exact stats and grid themes, and it is on from the first open: each machine gets a 30-day pro trial with no key to enter, and the status bar counts it down from "Pro trial, 30 days left".

Free - the full viewer, for files of any size

• Metadata-first open: a parquet file shows its schema, row count and row groups from the footer before any data decodes, whatever the file size.
• Exact types: a virtualized table with int64 and decimals at full precision, timestamps with their unit and timezone, nested lists, structs and maps as JSON.
• Whole-file search: match navigation, case toggle and matches only, which pages through the hit rows alone.
• Go to row: Ctrl+G, the row, Enter.
• Schema view: logical and physical types, nullability, codecs, encodings, and the footer's per-column null counts and min/max.
• Row detail: pretty-printed values and one-click copy; copy visible rows as CSV.
• Codecs and framing: parquet snappy, gzip, zstd, lz4 and lz4_raw, plus lz4- and zstd-compressed feather batches; Arrow IPC file and stream, including dictionary-encoded columns and legacy v4 framing.
• Avro: object containers, with the row count from the block headers, so the last row of a big file is one jump away; codecs null, deflate, snappy and zstandard; nested records, arrays and maps show as readable cells, and decimals, dates, times, timestamps and uuids decode to their values.
• TFRecord: tf.Example and tf.SequenceExample records, gzip or zlib compressed too; both checksums of every record are verified at open; each feature key becomes a column, a feature with one value shows as a plain cell and longer ones as a list; image bytes show their type and size instead of hex.
• Open With: an Open With editor and the default for these binary formats.
• Private: runs locally. no account, no telemetry. the free viewer makes no network calls; a key makes one activation call when you paste it, a license check about once a month after that, and one release call when you remove it. the trial start is kept in .twilightventures-lens.json in your home folder as well as in VS Code.

for a parquet file the row count and the schema come from the footer before any row decodes, and the grid asks for rows in pages of 200 as you scroll, read from the file by position. a list, struct or map column stays one column under its schema name, with the value rendered as JSON in the cell, clipped at 200 characters there and shown whole in the row detail. a timestamp column reads as a date and time to the microsecond, with UTC after it when the file stores the value as UTC-adjusted, rather than as an integer. the extension runs on VS Code 1.90 or newer. it claims .parquet, .pq, .parq, .avro, .tfrecord, .tfrecords, .tfrec, .tfrecord.gz, .arrow, .arrows, .ipc, .feather and .ftr, and nothing else: a .csv or .json file is not touched. the status bar item shows only while a Parquet Lens tab is active; the pro dialog appears only when you click a pro item.

Pro, optional one-time purchase

• Filter queries: country == "US" && amount > 100, tested against every row with the column's own type; the grid becomes the matching rows, search runs inside them, and export can take them.
• Export: all rows, filter matches or search matches, to csv or jsonl, with a cancelable progress bar. never over the source file.
• Exact stats: the schema view's full scan computes nulls, min, max, mean and distinct counts from every row instead of the footer statistics.
• Themes: twelve looks for the grid: default, hacker, cyberpunk, goblincore, neon, nosferatu, halloween, blue lagoon, duskhollow, abyss, obsidian and moonlit garden, each tuned for light and dark editors. run Parquet Lens: Pick theme to try one; trying is free for the window, keeping it is pro. the default look never changes.

the trial has three notices, each shown when a Parquet Lens tab is in front. one comes inside the last seven days, with the days left in it rather than seven every time, and another on the final day; those two stay out of a sitting that asks you for a review, and never both show in one session. a third comes once the trial has ended. it reads "Your Lens Pro trial has ended. Get Lens Pro to keep whole-file filters, export, exact stats and themes.", and after it the free viewer stays as it was. a machine sees each of the three once, and a key entered stops all of them. all three carry the Get Lens Pro button, which opens the same checkout the status bar item does. every pro dialog names the feature, "Whole-file filter is a Lens Pro feature." for the filter box, and offers the same two buttons, Enter license key and Get Pro; the command palette has the pair as Parquet Lens: Get Lens Pro and Parquet Lens: Enter license key, and the status bar item opens a menu with both.

one Lens Pro key covers Parquet Lens, JSONL Lens and Log Lens for VS Code, but the three do not pass the key between them. paste it into each one you use; the Remove license key command in that extension releases that activation again.

$49 personal, $99 business, one-time, includes 12 months of updates: the key unlocks Pro in every build released within a year of the purchase and keeps working in those builds; a build released after that runs as the free viewer until a new key. a personal key activates on up to 3 machines, a business key on 10, all three extensions on each (each extension on each machine is one activation: 9 on the personal key, 30 on the business key); release a machine any time from the Polar customer portal.

buy on polar (personal, business), then run Parquet Lens: Enter license key.

receipts, invoices, your key and its activations are in the Polar customer portal at polar.sh/twilight-ventures/portal. sign in with the purchase email. for a refund, write to support@twilightventures.dev. a refund revokes the key.

the free viewer is the complete viewer, not a demo. everything that was free in 0.1.0 stays free in every later build; pro adds the four items above and nothing is taken away.

Part of the Lens family

• JSONL Lens for VS Code: the same table, search and schema view for JSON Lines files; a jsonl export from here opens straight in it.
• On JetBrains IDEs: Parquet Lens, JSONL Lens and Log Lens - one engine, a shared filter grammar, exports that open in each other.

Guides and support

the guides and the family overview are at twilightventures.dev. write to support@twilightventures.dev about anything to do with Parquet Lens or a purchase, suggestions included; for a bug, name the version and the rough size of the file. bugs and requests can also go on the issues page of the Lens repository.