diff --git a/DESCRIPTION b/DESCRIPTION
index b52ce12..a7efcd4 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: r.releases.utils
 Title: Utilities for An R Universe of Package Releases
 Description: Utilities for an R universe of package releases.
-Version: 0.0.7.9000
+Version: 0.0.8
 License: MIT + file LICENSE
 URL:
   https://r-releases.github.io/r.releases.utils/,
diff --git a/NAMESPACE b/NAMESPACE
index d11de82..4f22f63 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -4,12 +4,14 @@ export(assert_cran_url)
 export(assert_package)
 export(assert_release_exists)
 export(build_universe)
+export(record_versions)
 export(review_pull_request)
 export(review_pull_requests)
 export(try_message)
 importFrom(gh,gh)
 importFrom(jsonlite,parse_json)
 importFrom(jsonlite,read_json)
+importFrom(jsonlite,write_json)
 importFrom(nanonext,ncurl)
 importFrom(nanonext,parse_url)
 importFrom(nanonext,status_code)
diff --git a/NEWS.md b/NEWS.md
index 0ff4ff0..8b9f519 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,7 +1,8 @@
-# r.releases.utils 0.0.7.9000 (development)
+# r.releases.utils 0.0.8
 
 * Use R-releases and not `r-releases` to refer to the project.
 * Edit bot messages.
+* Add `record_versions()`.
 
 # r.releases.utils 0.0.7
 
diff --git a/R/package.R b/R/package.R
index f73f627..edd0f84 100644
--- a/R/package.R
+++ b/R/package.R
@@ -3,7 +3,7 @@
 #' @name r.releases.utils-package
 #' @family help
 #' @importFrom gh gh
-#' @importFrom jsonlite parse_json read_json
+#' @importFrom jsonlite parse_json read_json write_json
 #' @importFrom nanonext ncurl parse_url status_code
 #' @importFrom pkgsearch cran_package
 #' @importFrom vctrs vec_rbind
diff --git a/R/record_versions.R b/R/record_versions.R
new file mode 100644
index 0000000..9cac95f
--- /dev/null
+++ b/R/record_versions.R
@@ -0,0 +1,71 @@
+#' @title Record the manifest of package versions.
+#' @export
+#' @keywords internal
+#' @description Record the manifest of versions of packages
+#'   and their MD5 hashes.
+#' @details As well as their versions and MD5 hashes, this function
+#'   records the highest version ever recorded and the MD5 of that
+#'   version. This information helps check if a package complies with
+#'   best practices for version numbers: the version number should increment
+#'   on each new release.
+#' @return `NULL` (invisibly). Writes a package manifest as a JSON file.
+#' @param manifest Character of length 1, file path to the JSON manifest.
+#' @param repos Character string of package repositories to track.
+record_versions <- function(
+  manifest = "versions.json",
+  repos = "https://r-releases.r-universe.dev"
+) {
+  current <- get_versions(repos = repos)
+  if (!file.exists(manifest)) {
+    jsonlite::write_json(x = current, path = manifest, pretty = TRUE)
+    return(invisible())
+  }
+  previous <- read_previous(manifest = manifest)
+  new <- update_manifest(current = current, previous = previous)
+  jsonlite::write_json(x = new, path = manifest, pretty = TRUE)
+}
+
+get_versions <- function(repos) {
+  out <- available.packages(repos = "https://r-releases.r-universe.dev")
+  out <- as.data.frame(out)
+  out <- out[, c("Package", "Version", "MD5sum")]
+  colnames(out) <- c("package", "version_current", "md5_current")
+  rownames(out) <- NULL
+  out
+}
+
+read_previous <- function(manifest) {
+  out <- jsonlite::read_json(path = manifest)
+  out <- do.call(what = vctrs::vec_rbind, args = out)
+  for (field in colnames(out)) {
+    out[[field]] <- as.character(out[[field]])
+  }
+  if (is.null(out$version_highest)) {
+    out$version_highest <- out$version_current
+  }
+  if (is.null(out$md5_highest)) {
+    out$md5_highest <- out$md5_current
+  }
+  out$version_current <- NULL
+  out$md5_current <- NULL
+  out
+}
+
+update_manifest <- function(current, previous) {
+  new <- merge(x = current, y = previous, all = TRUE)
+  incremented <- apply(
+    X = new,
+    MARGIN = 1L,
+    FUN = function(row) {
+      print(.subset2(row, "version_current"))
+      print(.subset2(row, "version_highest"))
+      utils::compareVersion(
+        a = .subset2(row, "version_current"),
+        b = .subset2(row, "version_highest")
+      ) > 0.5
+    }
+  )
+  new$version_highest[incremented] <- new$version_current[incremented]
+  new$md5_highest[incremented] <- new$md5_current[incremented]
+  new
+}
diff --git a/man/record_versions.Rd b/man/record_versions.Rd
new file mode 100644
index 0000000..179ac55
--- /dev/null
+++ b/man/record_versions.Rd
@@ -0,0 +1,31 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/record_versions.R
+\name{record_versions}
+\alias{record_versions}
+\title{Record the manifest of package versions.}
+\usage{
+record_versions(
+  manifest = "versions.json",
+  repos = "https://r-releases.r-universe.dev"
+)
+}
+\arguments{
+\item{manifest}{Character of length 1, file path to the JSON manifest.}
+
+\item{repos}{Character string of package repositories to track.}
+}
+\value{
+\code{NULL} (invisibly). Writes a package manifest as a JSON file.
+}
+\description{
+Record the manifest of versions of packages
+and their MD5 hashes.
+}
+\details{
+As well as their versions and MD5 hashes, this function
+records the highest version ever recorded and the MD5 of that
+version. This information helps check if a package complies with
+best practices for version numbers: the version number should increment
+on each new release.
+}
+\keyword{internal}