diff --git a/noodles-util/examples/util_alignment_rewrite_async.rs b/noodles-util/examples/util_alignment_rewrite_async.rs
new file mode 100644
index 000000000..f86e04884
--- /dev/null
+++ b/noodles-util/examples/util_alignment_rewrite_async.rs
@@ -0,0 +1,48 @@
+//! Rewrites an alignment format to another alignment format asynchronously.
+//!
+//! The output format is determined from the extension of the destination.
+
+use std::env;
+
+use futures::TryStreamExt;
+use noodles_fasta::{self as fasta, repository::adapters::IndexedReader};
+use noodles_util::alignment;
+use tokio::io;
+
+#[tokio::main]
+async fn main() -> io::Result<()> {
+    let mut args = env::args().skip(1);
+
+    let src = args.next().expect("missing src");
+    let dst = args.next().expect("missing dst");
+    let fasta_src = args.next();
+
+    let repository = fasta_src
+        .map(|src| fasta::io::indexed_reader::Builder::default().build_from_path(src))
+        .transpose()?
+        .map(IndexedReader::new)
+        .map(fasta::Repository::new)
+        .unwrap_or_default();
+
+    let mut reader = alignment::r#async::io::reader::Builder::default()
+        .set_reference_sequence_repository(repository.clone())
+        .build_from_path(src)
+        .await?;
+
+    let header = reader.read_header().await?;
+
+    let mut writer = alignment::r#async::io::writer::Builder::default()
+        .set_reference_sequence_repository(repository)
+        .build_from_path(dst)
+        .await?;
+
+    writer.write_header(&header).await?;
+
+    while let Some(record) = reader.records(&header).try_next().await? {
+        writer.write_record(&header, &record).await?;
+    }
+
+    writer.shutdown(&header).await?;
+
+    Ok(())
+}
diff --git a/noodles-util/src/alignment/async/io.rs b/noodles-util/src/alignment/async/io.rs
index 17b3f262f..641d42c3e 100644
--- a/noodles-util/src/alignment/async/io.rs
+++ b/noodles-util/src/alignment/async/io.rs
@@ -1,5 +1,6 @@
 //! Async alignment format I/O.
 
 pub mod reader;
+pub mod writer;
 
-pub use self::reader::Reader;
+pub use self::{reader::Reader, writer::Writer};
diff --git a/noodles-util/src/alignment/async/io/writer.rs b/noodles-util/src/alignment/async/io/writer.rs
new file mode 100644
index 000000000..c0c156ab0
--- /dev/null
+++ b/noodles-util/src/alignment/async/io/writer.rs
@@ -0,0 +1,116 @@
+//! Async alignment writer.
+
+mod builder;
+
+use noodles_bam as bam;
+use noodles_cram as cram;
+use noodles_sam as sam;
+use tokio::io::{self, AsyncWrite};
+
+pub use self::builder::Builder;
+
+/// An async alignment writer.
+pub enum Writer<W: AsyncWrite> {
+    /// SAM.
+    Sam(sam::r#async::io::Writer<W>),
+    /// BAM.
+    Bam(bam::r#async::io::Writer<W>),
+    /// CRAM.
+    Cram(cram::r#async::io::Writer<W>),
+}
+
+impl<W> Writer<W>
+where
+    W: AsyncWrite + Unpin,
+{
+    /// Writes a SAM header.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[tokio::main]
+    /// # async fn main() -> tokio::io::Result<()> {
+    /// use noodles_sam as sam;
+    /// use noodles_util::alignment::r#async::io::writer::Builder;
+    /// use tokio::io::{self, AsyncWriteExt};
+    ///
+    /// let mut writer = Builder::default().build_from_writer(io::sink()).await?;
+    ///
+    /// let header = sam::Header::default();
+    /// writer.write_header(&header).await?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub async fn write_header(&mut self, header: &sam::Header) -> io::Result<()> {
+        match self {
+            Self::Sam(writer) => writer.write_header(header).await,
+            Self::Bam(writer) => writer.write_header(header).await,
+            Self::Cram(writer) => {
+                writer.write_file_definition().await?;
+                writer.write_file_header(header).await
+            }
+        }
+    }
+
+    /// Writes an alignment record.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[tokio::main]
+    /// # async fn main() -> tokio::io::Result<()> {
+    /// use noodles_sam as sam;
+    /// use noodles_util::alignment::r#async::io::writer::Builder;
+    /// use tokio::io::{self, AsyncWriteExt};
+    ///
+    /// let mut writer = Builder::default().build_from_writer(io::sink()).await?;
+    ///
+    /// let header = sam::Header::default();
+    /// let record = sam::Record::default();
+    /// writer.write_record(&header, &record).await?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub async fn write_record(
+        &mut self,
+        header: &sam::Header,
+        record: &dyn sam::alignment::Record,
+    ) -> io::Result<()> {
+        match self {
+            Self::Sam(writer) => writer.write_alignment_record(header, record).await,
+            Self::Bam(writer) => writer.write_alignment_record(header, record).await,
+            Self::Cram(writer) => {
+                let record = cram::Record::try_from_alignment_record(header, record)?;
+                writer.write_record(header, record).await
+            }
+        }
+    }
+
+    /// Shuts down the alignment format writer.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[tokio::main]
+    /// # async fn main() -> tokio::io::Result<()> {
+    /// use noodles_sam as sam;
+    /// use noodles_util::alignment::{self, io::Format};
+    /// use tokio::io;
+    ///
+    /// let mut writer = alignment::r#async::io::writer::Builder::default()
+    ///     .set_format(Format::Sam)
+    ///     .build_from_writer(io::sink()).await?;
+    ///
+    /// let header = sam::Header::default();
+    /// writer.shutdown(&header).await?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub async fn shutdown(&mut self, header: &sam::Header) -> io::Result<()> {
+        match self {
+            Self::Sam(_) => Ok(()),
+            Self::Bam(writer) => writer.shutdown().await,
+            Self::Cram(writer) => writer.shutdown(header).await,
+        }
+    }
+}
diff --git a/noodles-util/src/alignment/async/io/writer/builder.rs b/noodles-util/src/alignment/async/io/writer/builder.rs
new file mode 100644
index 000000000..278a75ca4
--- /dev/null
+++ b/noodles-util/src/alignment/async/io/writer/builder.rs
@@ -0,0 +1,187 @@
+use std::path::Path;
+
+use noodles_bam as bam;
+use noodles_bgzf as bgzf;
+use noodles_cram as cram;
+use noodles_fasta as fasta;
+use noodles_sam as sam;
+use tokio::{
+    fs::File,
+    io::{self, AsyncWrite},
+};
+
+use super::Writer;
+use crate::alignment::io::{CompressionMethod, Format};
+
+/// An async alignment writer builder.
+#[derive(Default)]
+pub struct Builder {
+    compression_method: Option<Option<CompressionMethod>>,
+    format: Option<Format>,
+    reference_sequence_repository: fasta::Repository,
+}
+
+impl Builder {
+    /// Sets the compression method.
+    ///
+    /// By default, the compression method is autodetected on build. This can be used to override
+    /// it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_util::alignment::{r#async::io::writer::Builder, io::CompressionMethod};
+    /// let builder = Builder::default().set_compression_method(Some(CompressionMethod::Bgzf));
+    /// ```
+    pub fn set_compression_method(mut self, compression_method: Option<CompressionMethod>) -> Self {
+        self.compression_method = Some(compression_method);
+        self
+    }
+
+    /// Sets the format of the output.
+    ///
+    /// By default, the format is autodetected on build. This can be used to override it.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_util::alignment::{r#async::io::writer::Builder, io::Format};
+    /// let builder = Builder::default().set_format(Format::Sam);
+    /// ```
+    pub fn set_format(mut self, format: Format) -> Self {
+        self.format = Some(format);
+        self
+    }
+
+    /// Sets the reference sequence repository.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use noodles_fasta as fasta;
+    /// use noodles_util::alignment::r#async::io::writer::Builder;
+    /// let repository = fasta::Repository::default();
+    /// let builder = Builder::default().set_reference_sequence_repository(repository);
+    /// ```
+    pub fn set_reference_sequence_repository(
+        mut self,
+        reference_sequence_repository: fasta::Repository,
+    ) -> Self {
+        self.reference_sequence_repository = reference_sequence_repository;
+        self
+    }
+
+    /// Builds an async alignment writer from a path.
+    ///
+    /// By default, the format and compression method will be detected from the path extension.
+    /// This can be overridden by using [`Self::set_format`] and [`Self::set_compression_method`].
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// # #[tokio::main]
+    /// # async fn main() -> tokio::io::Result<()> {
+    /// use noodles_util::alignment::r#async::io::reader::Builder;
+    /// let reader = Builder::default().build_from_path("sample.bam").await?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub async fn build_from_path<P>(
+        mut self,
+        src: P,
+    ) -> io::Result<Writer<Box<dyn AsyncWrite + Unpin>>>
+    where
+        P: AsRef<Path>,
+    {
+        use crate::alignment::io::writer::builder::{
+            detect_compression_method_from_path_extension, detect_format_from_path_extension,
+        };
+
+        let src = src.as_ref();
+
+        if self.compression_method.is_none() {
+            self.compression_method = Some(detect_compression_method_from_path_extension(src));
+        }
+
+        if self.format.is_none() {
+            self.format = detect_format_from_path_extension(src);
+        }
+
+        File::create(src)
+            .await
+            .map(|file| self.build_from_writer(file))?
+            .await
+    }
+
+    /// Builds an async alignment writer from a writer.
+    ///
+    /// If the format is not set, a default format is used. If the compression method is not set, a
+    /// default one is determined by the format.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// # #[tokio::main]
+    /// # async fn main() -> tokio::io::Result<()> {
+    /// use noodles_util::alignment::r#async::io::writer::Builder;
+    /// use tokio::io;
+    ///
+    /// let reader = Builder::default().build_from_writer(io::sink()).await?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    pub async fn build_from_writer<W>(
+        self,
+        writer: W,
+    ) -> io::Result<Writer<Box<dyn AsyncWrite + Unpin>>>
+    where
+        W: AsyncWrite + Unpin + 'static,
+    {
+        use bam::r#async::io::Writer as AsyncBamWriter;
+        use sam::r#async::io::Writer as AsyncSamWriter;
+
+        let format = self.format.unwrap_or(Format::Sam);
+
+        let compression_method = match self.compression_method {
+            Some(compression_method) => compression_method,
+            None => match format {
+                Format::Sam | Format::Cram => None,
+                Format::Bam => Some(CompressionMethod::Bgzf),
+            },
+        };
+
+        let writer = match (format, compression_method) {
+            (Format::Sam, None) => {
+                let inner: Box<dyn AsyncWrite + Unpin> = Box::new(writer);
+                Writer::Sam(AsyncSamWriter::new(inner))
+            }
+            (Format::Sam, Some(CompressionMethod::Bgzf)) => {
+                let encoder: Box<dyn AsyncWrite + Unpin> = Box::new(bgzf::AsyncWriter::new(writer));
+                Writer::Sam(AsyncSamWriter::new(encoder))
+            }
+            (Format::Bam, None) => {
+                let inner: Box<dyn AsyncWrite + Unpin> = Box::new(writer);
+                Writer::Bam(AsyncBamWriter::from(inner))
+            }
+            (Format::Bam, Some(CompressionMethod::Bgzf)) => {
+                let encoder: Box<dyn AsyncWrite + Unpin> = Box::new(bgzf::AsyncWriter::new(writer));
+                Writer::Bam(AsyncBamWriter::from(encoder))
+            }
+            (Format::Cram, None) => {
+                let inner: Box<dyn AsyncWrite + Unpin> = Box::new(writer);
+                let inner = cram::r#async::io::writer::Builder::default()
+                    .set_reference_sequence_repository(self.reference_sequence_repository)
+                    .build_with_writer(inner);
+                Writer::Cram(inner)
+            }
+            (Format::Cram, Some(CompressionMethod::Bgzf)) => {
+                return Err(io::Error::new(
+                    io::ErrorKind::InvalidData,
+                    "CRAM cannot be compressed with BGZF",
+                ));
+            }
+        };
+
+        Ok(writer)
+    }
+}
diff --git a/noodles-util/src/alignment/io/writer/builder.rs b/noodles-util/src/alignment/io/writer/builder.rs
index 0a3063eee..314f1aba0 100644
--- a/noodles-util/src/alignment/io/writer/builder.rs
+++ b/noodles-util/src/alignment/io/writer/builder.rs
@@ -186,7 +186,7 @@ impl Builder {
     }
 }
 
-fn detect_compression_method_from_path_extension<P>(path: P) -> Option<CompressionMethod>
+pub(crate) fn detect_compression_method_from_path_extension<P>(path: P) -> Option<CompressionMethod>
 where
     P: AsRef<Path>,
 {
@@ -196,7 +196,7 @@ where
     }
 }
 
-fn detect_format_from_path_extension<P>(path: P) -> Option<Format>
+pub(crate) fn detect_format_from_path_extension<P>(path: P) -> Option<Format>
 where
     P: AsRef<Path>,
 {