diff --git a/index-scheduler/src/document_formats.rs b/index-scheduler/src/document_formats.rs
new file mode 100644
index 000000000..ebc98f3fb
--- /dev/null
+++ b/index-scheduler/src/document_formats.rs
@@ -0,0 +1,155 @@
+use std::borrow::Borrow;
+use std::fmt::{self, Debug, Display};
+use std::io::{self, BufReader, Read, Seek, Write};
+
+use either::Either;
+use meilisearch_types::error::{Code, ErrorCode};
+use meilisearch_types::internal_error;
+use milli::documents::{DocumentsBatchBuilder, Error};
+use milli::Object;
+use serde::Deserialize;
+
+type Result<T> = std::result::Result<T, DocumentFormatError>;
+
+#[derive(Debug)]
+pub enum PayloadType {
+    Ndjson,
+    Json,
+    Csv,
+}
+
+impl fmt::Display for PayloadType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            PayloadType::Ndjson => f.write_str("ndjson"),
+            PayloadType::Json => f.write_str("json"),
+            PayloadType::Csv => f.write_str("csv"),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum DocumentFormatError {
+    Internal(Box<dyn std::error::Error + Send + Sync + 'static>),
+    MalformedPayload(Error, PayloadType),
+}
+
+impl Display for DocumentFormatError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Internal(e) => write!(f, "An internal error has occurred: `{}`.", e),
+            Self::MalformedPayload(me, b) => match me.borrow() {
+                Error::Json(se) => {
+                    // https://github.com/meilisearch/meilisearch/issues/2107
+                    // The user input maybe insanely long. We need to truncate it.
+                    let mut serde_msg = se.to_string();
+                    let ellipsis = "...";
+                    if serde_msg.len() > 100 + ellipsis.len() {
+                        serde_msg.replace_range(50..serde_msg.len() - 85, ellipsis);
+                    }
+
+                    write!(
+                        f,
+                        "The `{}` payload provided is malformed. `Couldn't serialize document value: {}`.",
+                        b, serde_msg
+                )
+                }
+                _ => write!(f, "The `{}` payload provided is malformed: `{}`.", b, me),
+            },
+        }
+    }
+}
+
+impl std::error::Error for DocumentFormatError {}
+
+impl From<(PayloadType, Error)> for DocumentFormatError {
+    fn from((ty, error): (PayloadType, Error)) -> Self {
+        match error {
+            Error::Io(e) => Self::Internal(Box::new(e)),
+            e => Self::MalformedPayload(e, ty),
+        }
+    }
+}
+
+impl ErrorCode for DocumentFormatError {
+    fn error_code(&self) -> Code {
+        match self {
+            DocumentFormatError::Internal(_) => Code::Internal,
+            DocumentFormatError::MalformedPayload(_, _) => Code::MalformedPayload,
+        }
+    }
+}
+
+internal_error!(DocumentFormatError: io::Error);
+
+/// Reads CSV from input and write an obkv batch to writer.
+pub fn read_csv(input: impl Read, writer: impl Write + Seek) -> Result<usize> {
+    let mut builder = DocumentsBatchBuilder::new(writer);
+
+    let csv = csv::Reader::from_reader(input);
+    builder.append_csv(csv).map_err(|e| (PayloadType::Csv, e))?;
+
+    let count = builder.documents_count();
+    let _ = builder
+        .into_inner()
+        .map_err(Into::into)
+        .map_err(DocumentFormatError::Internal)?;
+
+    Ok(count as usize)
+}
+
+/// Reads JSON Lines from input and write an obkv batch to writer.
+pub fn read_ndjson(input: impl Read, writer: impl Write + Seek) -> Result<usize> {
+    let mut builder = DocumentsBatchBuilder::new(writer);
+    let reader = BufReader::new(input);
+
+    for result in serde_json::Deserializer::from_reader(reader).into_iter() {
+        let object = result
+            .map_err(Error::Json)
+            .map_err(|e| (PayloadType::Ndjson, e))?;
+        builder
+            .append_json_object(&object)
+            .map_err(Into::into)
+            .map_err(DocumentFormatError::Internal)?;
+    }
+
+    let count = builder.documents_count();
+    let _ = builder
+        .into_inner()
+        .map_err(Into::into)
+        .map_err(DocumentFormatError::Internal)?;
+
+    Ok(count as usize)
+}
+
+/// Reads JSON from input and write an obkv batch to writer.
+pub fn read_json(input: impl Read, writer: impl Write + Seek) -> Result<usize> {
+    let mut builder = DocumentsBatchBuilder::new(writer);
+    let reader = BufReader::new(input);
+
+    #[derive(Deserialize, Debug)]
+    #[serde(transparent)]
+    struct ArrayOrSingleObject {
+        #[serde(with = "either::serde_untagged")]
+        inner: Either<Vec<Object>, Object>,
+    }
+
+    let content: ArrayOrSingleObject = serde_json::from_reader(reader)
+        .map_err(Error::Json)
+        .map_err(|e| (PayloadType::Json, e))?;
+
+    for object in content.inner.map_right(|o| vec![o]).into_inner() {
+        builder
+            .append_json_object(&object)
+            .map_err(Into::into)
+            .map_err(DocumentFormatError::Internal)?;
+    }
+
+    let count = builder.documents_count();
+    let _ = builder
+        .into_inner()
+        .map_err(Into::into)
+        .map_err(DocumentFormatError::Internal)?;
+
+    Ok(count as usize)
+}