diff --git a/README.md b/README.md
index 2f943ea..0e6e185 100644
--- a/README.md
+++ b/README.md
@@ -6,14 +6,20 @@
 [![minzipped](https://img.shields.io/bundlephobia/minzip/hyparquet-writer)](https://www.npmjs.com/package/hyparquet-writer)
 [![workflow status](https://github.com/hyparam/hyparquet-writer/actions/workflows/ci.yml/badge.svg)](https://github.com/hyparam/hyparquet-writer/actions)
 [![mit license](https://img.shields.io/badge/License-MIT-orange.svg)](https://opensource.org/licenses/MIT)
-![coverage](https://img.shields.io/badge/Coverage-96-darkred)
+![coverage](https://img.shields.io/badge/Coverage-97-darkred)
 [![dependencies](https://img.shields.io/badge/Dependencies-1-blueviolet)](https://www.npmjs.com/package/hyparquet-writer?activeTab=dependencies)
 
 Hyparquet Writer is a JavaScript library for writing [Apache Parquet](https://parquet.apache.org) files. It is designed to be lightweight, fast and store data very efficiently. It is a companion to the [hyparquet](https://github.com/hyparam/hyparquet) library, which is a JavaScript library for reading parquet files.
 
 ## Usage
 
-Call `parquetWrite` with a list of columns, each column is an object with a `name` and `data` field. The `data` field should be an array of same-type values.
+Call `parquetWrite` with argument `columnData`. Each column in `columnData` should contain:
+
+- `name`: the column name
+- `data`: an array of same-type values
+- `type`: the parquet schema type (optional, type guessed from data if not provided)
+
+Example:
 
 ```javascript
 import { parquetWrite } from 'hyparquet-writer'
@@ -28,11 +34,31 @@ const arrayBuffer = parquetWrite({
 
 ## Options
 
+Options can be passed to `parquetWrite` to change parquet file properties:
+
  - `compression`: use snappy compression (default true)
  - `statistics`: write column statistics (default true)
  - `rowGroupSize`: number of rows in each row group (default 100000)
  - `kvMetadata`: extra key-value metadata
 
+```javascript
+import { parquetWrite } from 'hyparquet-writer'
+
+const arrayBuffer = parquetWrite({
+  columnData: [
+    { name: 'name', data: ['Alice', 'Bob', 'Charlie'], type: 'STRING' },
+    { name: 'age', data: [25, 30, 35], type: 'INT32' },
+  ],
+  compression: false,
+  statistics: false,
+  rowGroupSize: 1000,
+  kvMetadata: {
+    'key1': 'value1',
+    'key2': 'value2',
+  },
+})
+```
+
 ## References
 
  - https://github.com/hyparam/hyparquet
diff --git a/package.json b/package.json
index 4fb9f50..191c9fb 100644
--- a/package.json
+++ b/package.json
@@ -40,7 +40,7 @@
     "test": "vitest run"
   },
   "dependencies": {
-    "hyparquet": "1.10.4"
+    "hyparquet": "1.11.0"
   },
   "devDependencies": {
     "@babel/eslint-parser": "7.27.0",
diff --git a/src/writer.js b/src/bytewriter.js
similarity index 72%
rename from src/writer.js
rename to src/bytewriter.js
index b83d593..58f5037 100644
--- a/src/writer.js
+++ b/src/bytewriter.js
@@ -1,10 +1,11 @@
 
 /**
- * Self-expanding buffer view
+ * Generic buffered writer.
  *
- * @returns {import('../src/types.js').Writer}
+ * @import {Writer} from '../src/types.js'
+ * @returns {Writer}
  */
-export function Writer() {
+export function ByteWriter() {
   this.buffer = new ArrayBuffer(1024)
   this.offset = 0
   this.view = new DataView(this.buffer)
@@ -14,24 +15,29 @@ export function Writer() {
 /**
  * @param {number} size
  */
-Writer.prototype.ensure = function(size) {
+ByteWriter.prototype.ensure = function(size) {
+  // auto-expanding buffer
   if (this.offset + size > this.buffer.byteLength) {
     const newSize = Math.max(this.buffer.byteLength * 2, this.offset + size)
     const newBuffer = new ArrayBuffer(newSize)
+    // TODO: save buffers until later and merge once?
     new Uint8Array(newBuffer).set(new Uint8Array(this.buffer))
     this.buffer = newBuffer
     this.view = new DataView(this.buffer)
   }
 }
 
-Writer.prototype.getBuffer = function() {
+ByteWriter.prototype.finish = function() {
+}
+
+ByteWriter.prototype.getBuffer = function() {
   return this.buffer.slice(0, this.offset)
 }
 
 /**
  * @param {number} value
  */
-Writer.prototype.appendUint8 = function(value) {
+ByteWriter.prototype.appendUint8 = function(value) {
   this.ensure(this.offset + 1)
   this.view.setUint8(this.offset, value)
   this.offset++
@@ -40,7 +46,7 @@ Writer.prototype.appendUint8 = function(value) {
 /**
  * @param {number} value
  */
-Writer.prototype.appendUint32 = function(value) {
+ByteWriter.prototype.appendUint32 = function(value) {
   this.ensure(this.offset + 4)
   this.view.setUint32(this.offset, value, true)
   this.offset += 4
@@ -49,7 +55,7 @@ Writer.prototype.appendUint32 = function(value) {
 /**
  * @param {number} value
  */
-Writer.prototype.appendInt32 = function(value) {
+ByteWriter.prototype.appendInt32 = function(value) {
   this.ensure(this.offset + 4)
   this.view.setInt32(this.offset, value, true)
   this.offset += 4
@@ -58,7 +64,7 @@ Writer.prototype.appendInt32 = function(value) {
 /**
  * @param {bigint} value
  */
-Writer.prototype.appendInt64 = function(value) {
+ByteWriter.prototype.appendInt64 = function(value) {
   this.ensure(this.offset + 8)
   this.view.setBigInt64(this.offset, BigInt(value), true)
   this.offset += 8
@@ -67,7 +73,7 @@ Writer.prototype.appendInt64 = function(value) {
 /**
  * @param {number} value
  */
-Writer.prototype.appendFloat64 = function(value) {
+ByteWriter.prototype.appendFloat64 = function(value) {
   this.ensure(this.offset + 8)
   this.view.setFloat64(this.offset, value, true)
   this.offset += 8
@@ -76,14 +82,14 @@ Writer.prototype.appendFloat64 = function(value) {
 /**
  * @param {ArrayBuffer} value
  */
-Writer.prototype.appendBuffer = function(value) {
+ByteWriter.prototype.appendBuffer = function(value) {
   this.appendBytes(new Uint8Array(value))
 }
 
 /**
  * @param {Uint8Array} value
  */
-Writer.prototype.appendBytes = function(value) {
+ByteWriter.prototype.appendBytes = function(value) {
   this.ensure(this.offset + value.length)
   new Uint8Array(this.buffer, this.offset, value.length).set(value)
   this.offset += value.length
@@ -95,7 +101,7 @@ Writer.prototype.appendBytes = function(value) {
  *
  * @param {number} value
  */
-Writer.prototype.appendVarInt = function(value) {
+ByteWriter.prototype.appendVarInt = function(value) {
   while (true) {
     if ((value & ~0x7f) === 0) {
       // fits in 7 bits
@@ -114,7 +120,7 @@ Writer.prototype.appendVarInt = function(value) {
  *
  * @param {bigint} value
  */
-Writer.prototype.appendVarBigInt = function(value) {
+ByteWriter.prototype.appendVarBigInt = function(value) {
   while (true) {
     if ((value & ~0x7fn) === 0n) {
       // fits in 7 bits
diff --git a/src/column.js b/src/column.js
index 8a3aeac..fc575e7 100644
--- a/src/column.js
+++ b/src/column.js
@@ -5,10 +5,11 @@ import { writePlain } from './plain.js'
 import { getMaxDefinitionLevel, getMaxRepetitionLevel } from './schema.js'
 import { snappyCompress } from './snappy.js'
 import { serializeTCompactProtocol } from './thrift.js'
-import { Writer } from './writer.js'
+import { ByteWriter } from './bytewriter.js'
 
 /**
  * @import {ColumnMetaData, DecodedArray, PageHeader, ParquetType, SchemaElement, Statistics} from 'hyparquet'
+ * @import {Writer} from '../src/types.js'
  * @param {Writer} writer
  * @param {SchemaElement[]} schemaPath
  * @param {DecodedArray} values
@@ -50,7 +51,7 @@ export function writeColumn(writer, schemaPath, values, compressed, stats) {
   }
 
   // Write levels to temp buffer
-  const levels = new Writer()
+  const levels = new ByteWriter()
   const { definition_levels_byte_length, repetition_levels_byte_length, num_nulls } = writeLevels(levels, schemaPath, values)
 
   // dictionary encoding
@@ -81,7 +82,7 @@ export function writeColumn(writer, schemaPath, values, compressed, stats) {
   }
 
   // write page data to temp buffer
-  const page = new Writer()
+  const page = new ByteWriter()
   /** @type {import('hyparquet').Encoding} */
   const encoding = dictionary ? 'RLE_DICTIONARY' : 'PLAIN'
   if (dictionary) {
@@ -95,7 +96,7 @@ export function writeColumn(writer, schemaPath, values, compressed, stats) {
   // compress page data
   let compressedPage = page
   if (compressed) {
-    compressedPage = new Writer()
+    compressedPage = new ByteWriter()
     snappyCompress(compressedPage, new Uint8Array(page.getBuffer()))
   }
 
@@ -187,13 +188,13 @@ function useDictionary(values, type) {
  * @param {boolean} compressed
  */
 function writeDictionaryPage(writer, dictionary, type, compressed) {
-  const dictionaryPage = new Writer()
+  const dictionaryPage = new ByteWriter()
   writePlain(dictionaryPage, dictionary, type)
 
   // compress dictionary page data
   let compressedDictionaryPage = dictionaryPage
   if (compressed) {
-    compressedDictionaryPage = new Writer()
+    compressedDictionaryPage = new ByteWriter()
     snappyCompress(compressedDictionaryPage, new Uint8Array(dictionaryPage.getBuffer()))
   }
 
diff --git a/src/encoding.js b/src/encoding.js
index 661fc1e..1df397d 100644
--- a/src/encoding.js
+++ b/src/encoding.js
@@ -1,7 +1,8 @@
-import { Writer } from './writer.js'
+import { ByteWriter } from './bytewriter.js'
 
 /**
  * @import {DecodedArray} from 'hyparquet'
+ * @import {Writer} from '../src/types.js'
  * @param {Writer} writer
  * @param {DecodedArray} values
  * @returns {number} bytes written
@@ -12,9 +13,9 @@ export function writeRleBitPackedHybrid(writer, values) {
   const bitWidth = Math.ceil(Math.log2(Math.max(...values) + 1))
 
   // try both RLE and bit-packed and choose the best
-  const rle = new Writer()
+  const rle = new ByteWriter()
   writeRle(rle, values, bitWidth)
-  const bitPacked = new Writer()
+  const bitPacked = new ByteWriter()
   writeBitPacked(bitPacked, values, bitWidth)
 
   if (rle.offset < bitPacked.offset) {
diff --git a/src/metadata.js b/src/metadata.js
index f6a8456..198fd29 100644
--- a/src/metadata.js
+++ b/src/metadata.js
@@ -4,7 +4,7 @@ import { unconvertMetadata } from './unconvert.js'
 
 /**
  * @import {FileMetaData} from 'hyparquet'
- * @import {Writer} from './writer.js'
+ * @import {Writer} from '../src/types.js'
  * @param {Writer} writer
  * @param {FileMetaData} metadata
  */
diff --git a/src/parquet-writer.js b/src/parquet-writer.js
index de3305c..82c3e24 100644
--- a/src/parquet-writer.js
+++ b/src/parquet-writer.js
@@ -1,28 +1,29 @@
 import { writeColumn } from './column.js'
-import { Writer } from './writer.js'
 import { writeMetadata } from './metadata.js'
 
 /**
  * Create a new ParquetWriter.
  *
- * @import {ColumnChunk, FileMetaData, RowGroup, SchemaElement, SchemaTree} from 'hyparquet'
+ * @import {ColumnChunk, FileMetaData, RowGroup, SchemaElement} from 'hyparquet'
  * @import {KeyValue} from 'hyparquet/src/types.js'
- * @import {ColumnData} from './types.js'
+ * @import {ColumnData, Writer} from '../src/types.js'
  * @param {object} options
+ * @param {Writer} options.writer
  * @param {SchemaElement[]} options.schema
  * @param {boolean} [options.compressed]
  * @param {boolean} [options.statistics]
  * @param {KeyValue[]} [options.kvMetadata]
  */
-export function ParquetWriter({ schema, compressed = true, statistics = true, kvMetadata }) {
-  /** @type {RowGroup[]} */
-  this.row_groups = []
+export function ParquetWriter({ writer, schema, compressed = true, statistics = true, kvMetadata }) {
+  this.writer = writer
   this.schema = schema
   this.compressed = compressed
   this.statistics = statistics
   this.kvMetadata = kvMetadata
+
+  /** @type {RowGroup[]} */
+  this.row_groups = []
   this.num_rows = BigInt(0)
-  this.writer = new Writer()
 
   // write header PAR1
   this.writer.appendUint32(0x31524150)
@@ -72,9 +73,7 @@ ParquetWriter.prototype.write = function({ columnData, rowGroupSize = 100000 })
 }
 
 /**
- * Finish writing the file and return the buffer.
- *
- * @returns {ArrayBuffer}
+ * Finish writing the file.
  */
 ParquetWriter.prototype.finish = function() {
   // write metadata
@@ -94,6 +93,5 @@ ParquetWriter.prototype.finish = function() {
 
   // write footer PAR1
   this.writer.appendUint32(0x31524150)
-
-  return this.writer.getBuffer()
+  this.writer.finish()
 }
diff --git a/src/plain.js b/src/plain.js
index a2f42ef..6cfdd1f 100644
--- a/src/plain.js
+++ b/src/plain.js
@@ -1,7 +1,7 @@
 
 /**
  * @import {DecodedArray, ParquetType} from 'hyparquet/src/types.js'
- * @import {Writer} from './writer.js'
+ * @import {Writer} from '../src/types.js'
  * @param {Writer} writer
  * @param {DecodedArray} values
  * @param {ParquetType} type
diff --git a/src/schema.js b/src/schema.js
index 2692773..df4fe51 100644
--- a/src/schema.js
+++ b/src/schema.js
@@ -95,3 +95,32 @@ export function getMaxDefinitionLevel(schemaPath) {
   }
   return maxLevel
 }
+
+/**
+ * Convert column data to schema.
+ *
+ * @import {ColumnData} from '../src/types.js'
+ * @param {ColumnData[]} columnData
+ * @returns {SchemaElement[]}
+ */
+export function schemaFromColumnData(columnData) {
+  /** @type {SchemaElement[]} */
+  const schema = [{
+    name: 'root',
+    num_children: columnData.length,
+  }]
+  let num_rows = 0
+  for (const { name, data, type } of columnData) {
+    // check if all columns have the same length
+    if (num_rows === 0) {
+      num_rows = data.length
+    } else if (num_rows !== data.length) {
+      throw new Error('columns must have the same length')
+    }
+    // auto-detect type
+    const schemaElement = getSchemaElementForValues(name, data, type)
+    if (!schemaElement.type) throw new Error(`column ${name} cannot determine type`)
+    schema.push(schemaElement)
+  }
+  return schema
+}
diff --git a/src/snappy.js b/src/snappy.js
index d83b4a1..85b32be 100644
--- a/src/snappy.js
+++ b/src/snappy.js
@@ -14,7 +14,7 @@ const globalHashTables = new Array(MAX_HASH_TABLE_BITS + 1)
  * Compress snappy data.
  * Writes Snappy-compressed bytes into a writer.
  *
- * @import {Writer} from '../src/writer.js'
+ * @import {Writer} from '../src/types.js'
  * @param {Writer} writer
  * @param {Uint8Array} input - uncompressed data
  */
diff --git a/src/types.d.ts b/src/types.d.ts
index 793dd90..edfa57f 100644
--- a/src/types.d.ts
+++ b/src/types.d.ts
@@ -9,6 +9,9 @@ export interface ColumnData {
 export interface Writer {
   buffer: ArrayBuffer
   offset: number
+  view: DataView
+  ensure(size: number): void
+  finish(): void
   getBuffer(): ArrayBuffer
   appendUint8(value: number): void
   appendUint32(value: number): void
diff --git a/src/write.js b/src/write.js
index 8cc3887..63c666e 100644
--- a/src/write.js
+++ b/src/write.js
@@ -1,10 +1,10 @@
-import { getSchemaElementForValues } from './schema.js'
 import { ParquetWriter } from './parquet-writer.js'
+import { schemaFromColumnData } from './schema.js'
+import { ByteWriter } from './bytewriter.js'
 
 /**
  * Write data as parquet to an ArrayBuffer
  *
- * @import {ColumnChunk, DecodedArray, FileMetaData, RowGroup, SchemaElement, SchemaTree} from 'hyparquet'
  * @import {KeyValue} from 'hyparquet/src/types.js'
  * @import {ColumnData} from '../src/types.js'
  * @param {object} options
@@ -17,45 +17,18 @@ import { ParquetWriter } from './parquet-writer.js'
  */
 export function parquetWrite({ columnData, compressed = true, statistics = true, rowGroupSize = 100000, kvMetadata }) {
   const schema = schemaFromColumnData(columnData)
-  const writer = new ParquetWriter({
+  const writer = new ByteWriter()
+  const pq = new ParquetWriter({
+    writer,
     schema,
     compressed,
     statistics,
     kvMetadata,
   })
-
-  writer.write({
+  pq.write({
     columnData,
     rowGroupSize,
   })
-
-  return writer.finish()
-}
-
-/**
- * Convert column data to schema.
- *
- * @param {ColumnData[]} columnData
- * @returns {SchemaElement[]}
- */
-function schemaFromColumnData(columnData) {
-  /** @type {SchemaElement[]} */
-  const schema = [{
-    name: 'root',
-    num_children: columnData.length,
-  }]
-  let num_rows = 0
-  for (const { name, data, type } of columnData) {
-    // check if all columns have the same length
-    if (num_rows === 0) {
-      num_rows = data.length
-    } else if (num_rows !== data.length) {
-      throw new Error('columns must have the same length')
-    }
-    // auto-detect type
-    const schemaElement = getSchemaElementForValues(name, data, type)
-    if (!schemaElement.type) throw new Error(`column ${name} cannot determine type`)
-    schema.push(schemaElement)
-  }
-  return schema
+  pq.finish()
+  return writer.getBuffer()
 }
diff --git a/test/bytewriter.test.js b/test/bytewriter.test.js
new file mode 100644
index 0000000..6e8cbc0
--- /dev/null
+++ b/test/bytewriter.test.js
@@ -0,0 +1,106 @@
+import { describe, expect, it } from 'vitest'
+import { ByteWriter } from '../src/bytewriter.js'
+
+describe('ByteWriter', () => {
+  it('initializes with correct defaults', () => {
+    const writer = new ByteWriter()
+    expect(writer.offset).toBe(0)
+    expect(writer.buffer.byteLength).toBe(1024)
+  })
+
+  it('appendUint8 writes single byte', () => {
+    const writer = new ByteWriter()
+    writer.appendUint8(255)
+    expect(new Uint8Array(writer.getBuffer())).toEqual(new Uint8Array([0xff]))
+  })
+
+  it('appendUint32 writes a 32-bit integer in little-endian', () => {
+    const writer = new ByteWriter()
+    writer.appendUint32(0x12345678)
+    expect(new Uint8Array(writer.getBuffer())).toEqual(
+      new Uint8Array([0x78, 0x56, 0x34, 0x12])
+    )
+  })
+
+  it('appendInt32 writes signed 32-bit integer in little-endian', () => {
+    const writer = new ByteWriter()
+    writer.appendInt32(-1)
+    expect(new Uint8Array(writer.getBuffer())).toEqual(
+      new Uint8Array([0xff, 0xff, 0xff, 0xff])
+    )
+  })
+
+  it('appendInt64 writes a 64-bit bigint in little-endian', () => {
+    const writer = new ByteWriter()
+    writer.appendInt64(0x1122334455667788n)
+    expect(new Uint8Array(writer.getBuffer())).toEqual(
+      new Uint8Array([0x88, 0x77, 0x66, 0x55, 0x44, 0x33, 0x22, 0x11])
+    )
+  })
+
+  it('appendFloat64 writes a 64-bit float in little-endian', () => {
+    const writer = new ByteWriter()
+    writer.appendFloat64(1.0)
+    expect(new Uint8Array(writer.getBuffer())).toEqual(
+      new Uint8Array([0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x3f])
+    )
+  })
+
+  it('appendBytes writes raw Uint8Array data', () => {
+    const writer = new ByteWriter()
+    writer.appendBytes(new Uint8Array([1, 2, 3, 4]))
+    expect(new Uint8Array(writer.getBuffer())).toEqual(new Uint8Array([1, 2, 3, 4]))
+  })
+
+  it('appendBuffer writes raw ArrayBuffer data', () => {
+    const writer = new ByteWriter()
+    const buf = new Uint8Array([10, 20, 30]).buffer
+    writer.appendBuffer(buf)
+    expect(new Uint8Array(writer.getBuffer())).toEqual(new Uint8Array([10, 20, 30]))
+  })
+
+  it('appendVarInt encodes 32-bit varint', () => {
+    const writer = new ByteWriter()
+    writer.appendVarInt(127)
+    writer.appendVarInt(128)
+    writer.appendVarInt(300)
+
+    expect(new Uint8Array(writer.getBuffer())).toEqual(
+      new Uint8Array([
+        0x7f, // 127
+        0x80, 0x01, // 128
+        0xac, 0x02, // 300
+      ])
+    )
+  })
+
+  it('appendVarBigInt encodes bigint varint', () => {
+    const writer = new ByteWriter()
+    writer.appendVarBigInt(127n)
+    writer.appendVarBigInt(128n)
+    writer.appendVarBigInt(300n)
+
+    expect(new Uint8Array(writer.getBuffer())).toEqual(
+      new Uint8Array([
+        0x7f, // 127
+        0x80, 0x01, // 128
+        0xac, 0x02, // 300
+      ])
+    )
+  })
+
+  it('expands buffer automatically when needed', () => {
+    const writer = new ByteWriter()
+    // force expansion by writing more than initial 1024 bytes
+    const largeArray = new Uint8Array(2000).fill(0xaa)
+    writer.appendBytes(largeArray)
+    expect(writer.buffer.byteLength).toBeGreaterThanOrEqual(2000)
+    expect(new Uint8Array(writer.getBuffer()).length).toBe(2000)
+  })
+
+  it('finish does nothing but is callable', () => {
+    const writer = new ByteWriter()
+    writer.finish()
+    expect(writer.getBuffer().byteLength).toBe(0)
+  })
+})
diff --git a/test/encoding.test.js b/test/encoding.test.js
index 71b728f..7aa134e 100644
--- a/test/encoding.test.js
+++ b/test/encoding.test.js
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest'
-import { Writer } from '../src/writer.js'
+import { ByteWriter } from '../src/bytewriter.js'
 import { writeRleBitPackedHybrid } from '../src/encoding.js'
 import { readRleBitPackedHybrid } from 'hyparquet/src/encoding.js'
 
@@ -13,7 +13,7 @@ function roundTripDeserialize(values) {
   const bitWidth = Math.ceil(Math.log2(Math.max(...values) + 1))
 
   // Serialize the values using writeRleBitPackedHybrid
-  const writer = new Writer()
+  const writer = new ByteWriter()
   writeRleBitPackedHybrid(writer, values)
   const buffer = writer.getBuffer()
   const reader = { view: new DataView(buffer), offset: 0 }
diff --git a/test/metadata.test.js b/test/metadata.test.js
index 3a3d2f5..4ef528d 100644
--- a/test/metadata.test.js
+++ b/test/metadata.test.js
@@ -1,6 +1,6 @@
 import { parquetMetadata } from 'hyparquet'
 import { describe, expect, it } from 'vitest'
-import { Writer } from '../src/writer.js'
+import { ByteWriter } from '../src/bytewriter.js'
 import { writeMetadata } from '../src/metadata.js'
 
 /**
@@ -145,7 +145,7 @@ export const exampleMetadata = {
 
 describe('writeMetadata', () => {
   it('writes metadata and parses in hyparquet', () => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
 
     // Write header PAR1
     writer.appendUint32(0x31524150)
diff --git a/test/plain.test.js b/test/plain.test.js
index 78113f7..96719bf 100644
--- a/test/plain.test.js
+++ b/test/plain.test.js
@@ -1,10 +1,10 @@
 import { describe, expect, it } from 'vitest'
-import { Writer } from '../src/writer.js'
+import { ByteWriter } from '../src/bytewriter.js'
 import { writePlain } from '../src/plain.js'
 
 describe('writePlain', () => {
   it('writes BOOLEAN (multiple of 8 bits, plus leftover)', () => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
     const booleans = [true, false, true, true, false, false, false, true, true]
     writePlain(writer, booleans, 'BOOLEAN')
 
@@ -14,7 +14,7 @@ describe('writePlain', () => {
   })
 
   it('writes INT32', () => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
     const ints = [0, 1, 255, 256, 65535, -1, -2147483648, 2147483647]
     writePlain(writer, ints, 'INT32')
 
@@ -28,7 +28,7 @@ describe('writePlain', () => {
   })
 
   it('writes INT64', () => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
     const bigints = [0n, 1n, 42n, BigInt(2 ** 53 - 1)]
     writePlain(writer, bigints, 'INT64')
 
@@ -42,7 +42,7 @@ describe('writePlain', () => {
   })
 
   it('writes DOUBLE', () => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
     const doubles = [0, 3.14, -2.71, Infinity, -Infinity, NaN]
     writePlain(writer, doubles, 'DOUBLE')
 
@@ -60,7 +60,7 @@ describe('writePlain', () => {
   })
 
   it('writes BYTE_ARRAY', () => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
     const strings = ['a', 'b', 'c', 'd']
     // strings must be pre-converted to Uint8Array
     const encoder = new TextEncoder()
@@ -81,7 +81,7 @@ describe('writePlain', () => {
   })
 
   it('throws error on unsupported type', () => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
     expect(() => writePlain(writer, [1, 2, 3], 'INT96'))
       .toThrow(/parquet unsupported type/i)
   })
diff --git a/test/snappy.test.js b/test/snappy.test.js
index 264c33d..b4a3322 100644
--- a/test/snappy.test.js
+++ b/test/snappy.test.js
@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest'
 import { snappyCompress } from '../src/snappy.js'
-import { Writer } from '../src/writer.js'
+import { ByteWriter } from '../src/bytewriter.js'
 import { snappyUncompress } from 'hyparquet'
 
 describe('snappy compress', () => {
@@ -42,7 +42,7 @@ describe('snappy compress', () => {
       uncompressed: new Uint8Array([5]),
     },
   ])('compresses valid input %p', ({ compressed, uncompressed }) => {
-    const writer = new Writer()
+    const writer = new ByteWriter()
     const encoder = new TextEncoder()
     const input = typeof uncompressed === 'string' ? encoder.encode(uncompressed) : new Uint8Array(uncompressed)
     snappyCompress(writer, input)
diff --git a/test/thrift.test.js b/test/thrift.test.js
index 6e07a19..d54114a 100644
--- a/test/thrift.test.js
+++ b/test/thrift.test.js
@@ -1,7 +1,7 @@
 import { deserializeTCompactProtocol } from 'hyparquet/src/thrift.js'
 import { describe, expect, it } from 'vitest'
 import { serializeTCompactProtocol } from '../src/thrift.js'
-import { Writer } from '../src/writer.js'
+import { ByteWriter } from '../src/bytewriter.js'
 
 /**
  * Utility to decode a Thrift-serialized buffer and return the parsed object.
@@ -28,7 +28,7 @@ describe('serializeTCompactProtocol', () => {
       field_9: new TextEncoder().encode('Hello, Thrift!'),
     }
 
-    const writer = new Writer()
+    const writer = new ByteWriter()
     serializeTCompactProtocol(writer, data)
     const buf = writer.buffer.slice(0, writer.offset)
     const result = roundTripDeserialize(buf)
@@ -59,7 +59,7 @@ describe('serializeTCompactProtocol', () => {
       field_2: [true, false, true, false],
     }
 
-    const writer = new Writer()
+    const writer = new ByteWriter()
     serializeTCompactProtocol(writer, data)
     const buf = writer.buffer.slice(0, writer.offset)
     const result = roundTripDeserialize(buf)
@@ -72,7 +72,7 @@ describe('serializeTCompactProtocol', () => {
 
   it('handles empty object (only STOP)', () => {
     const data = {}
-    const writer = new Writer()
+    const writer = new ByteWriter()
     serializeTCompactProtocol(writer, data)
     const buf = writer.buffer.slice(0, writer.offset)
     const arr = new Uint8Array(buf)
@@ -89,7 +89,7 @@ describe('serializeTCompactProtocol', () => {
       field_2: 2,
       field_1: 1, // field_1 is out of order (less than field_2)
     }
-    const writer = new Writer()
+    const writer = new ByteWriter()
     expect(() => serializeTCompactProtocol(writer, invalidData)).toThrow()
   })
 })