diff --git a/internal/reader/atom/atom_10_test.go b/internal/reader/atom/atom_10_test.go
index be6e9148..7b69f29d 100644
--- a/internal/reader/atom/atom_10_test.go
+++ b/internal/reader/atom/atom_10_test.go
@@ -217,12 +217,31 @@ func TestParseFeedURL(t *testing.T) {
 	}
 }
 
-func TestParseFeedWithRelativeURL(t *testing.T) {
+func TestParseFeedWithRelativeFeedURL(t *testing.T) {
+	data := `<?xml version="1.0" encoding="utf-8"?>
+	<feed xmlns="http://www.w3.org/2005/Atom">
+	  <title>Example Feed</title>
+	  <link rel="alternate" type="text/html" href="https://example.org/"/>
+	  <link rel="self" type="application/atom+xml" href="/feed"/>
+	  <updated>2003-12-13T18:30:02Z</updated>
+	</feed>`
+
+	feed, err := Parse("https://example.org/", bytes.NewReader([]byte(data)), "10")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.FeedURL != "https://example.org/feed" {
+		t.Errorf("Incorrect feed URL, got: %s", feed.FeedURL)
+	}
+}
+
+func TestParseFeedWithRelativeSiteURL(t *testing.T) {
 	data := `<?xml version="1.0" encoding="utf-8"?>
 	<feed xmlns="http://www.w3.org/2005/Atom">
 	  <title>Example Feed</title>
 	  <link href="/blog/atom.xml" rel="self" type="application/atom+xml"/>
-	  <link href="/blog"/>
+	  <link href="/blog "/>
 
 	  <entry>
 		<title>Test</title>
@@ -241,15 +260,47 @@ func TestParseFeedWithRelativeURL(t *testing.T) {
 	}
 
 	if feed.FeedURL != "https://example.org/blog/atom.xml" {
-		t.Errorf("Incorrect feed URL, got: %s", feed.FeedURL)
+		t.Errorf("Incorrect feed URL, got: %q", feed.FeedURL)
 	}
 
 	if feed.SiteURL != "https://example.org/blog" {
-		t.Errorf("Incorrect site URL, got: %s", feed.SiteURL)
+		t.Errorf("Incorrect site URL, got: %q", feed.SiteURL)
 	}
 
 	if feed.Entries[0].URL != "https://example.org/blog/article.html" {
-		t.Errorf("Incorrect entry URL, got: %s", feed.Entries[0].URL)
+		t.Errorf("Incorrect entry URL, got: %q", feed.Entries[0].URL)
+	}
+}
+
+func TestParseFeedSiteURLWithTrailingSpace(t *testing.T) {
+	data := `<?xml version="1.0" encoding="utf-8"?>
+	<feed xmlns="http://www.w3.org/2005/Atom">
+	  <link href="http://example.org "/>
+	</feed>`
+
+	feed, err := Parse("https://example.org/", bytes.NewReader([]byte(data)), "10")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.SiteURL != "http://example.org" {
+		t.Errorf("Incorrect site URL, got: %q", feed.SiteURL)
+	}
+}
+
+func TestParseFeedWithFeedURLWithTrailingSpace(t *testing.T) {
+	data := `<?xml version="1.0" encoding="utf-8"?>
+	<feed xmlns="http://www.w3.org/2005/Atom">
+		<link href="/blog/atom.xml  " rel="self" type="application/atom+xml"/>
+	</feed>`
+
+	feed, err := Parse("https://example.org/", bytes.NewReader([]byte(data)), "10")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.FeedURL != "https://example.org/blog/atom.xml" {
+		t.Errorf("Incorrect site URL, got: %q", feed.FeedURL)
 	}
 }
 
diff --git a/internal/reader/json/adapter.go b/internal/reader/json/adapter.go
index e944f75a..cf54100f 100644
--- a/internal/reader/json/adapter.go
+++ b/internal/reader/json/adapter.go
@@ -24,15 +24,15 @@ func NewJSONAdapter(jsonFeed *JSONFeed) *JSONAdapter {
 	return &JSONAdapter{jsonFeed}
 }
 
-func (j *JSONAdapter) BuildFeed(feedURL string) *model.Feed {
+func (j *JSONAdapter) BuildFeed(baseURL string) *model.Feed {
 	feed := &model.Feed{
 		Title:   strings.TrimSpace(j.jsonFeed.Title),
-		FeedURL: j.jsonFeed.FeedURL,
-		SiteURL: j.jsonFeed.HomePageURL,
+		FeedURL: strings.TrimSpace(j.jsonFeed.FeedURL),
+		SiteURL: strings.TrimSpace(j.jsonFeed.HomePageURL),
 	}
 
 	if feed.FeedURL == "" {
-		feed.FeedURL = feedURL
+		feed.FeedURL = strings.TrimSpace(baseURL)
 	}
 
 	// Fallback to the feed URL if the site URL is empty.
@@ -40,11 +40,11 @@ func (j *JSONAdapter) BuildFeed(feedURL string) *model.Feed {
 		feed.SiteURL = feed.FeedURL
 	}
 
-	if feedURL, err := urllib.AbsoluteURL(feedURL, j.jsonFeed.FeedURL); err == nil {
+	if feedURL, err := urllib.AbsoluteURL(baseURL, feed.FeedURL); err == nil {
 		feed.FeedURL = feedURL
 	}
 
-	if siteURL, err := urllib.AbsoluteURL(feedURL, j.jsonFeed.HomePageURL); err == nil {
+	if siteURL, err := urllib.AbsoluteURL(baseURL, feed.SiteURL); err == nil {
 		feed.SiteURL = siteURL
 	}
 
diff --git a/internal/reader/json/parser_test.go b/internal/reader/json/parser_test.go
index 8e4102e0..0bbd39ec 100644
--- a/internal/reader/json/parser_test.go
+++ b/internal/reader/json/parser_test.go
@@ -177,6 +177,82 @@ func TestParsePodcast(t *testing.T) {
 	}
 }
 
+func TestParseFeedWithFeedURLWithTrailingSpace(t *testing.T) {
+	data := `{
+		"version": "https://jsonfeed.org/version/1",
+		"title": "My Example Feed",
+		"home_page_url": "https://example.org/",
+		"feed_url": "https://example.org/feed.json ",
+		"items": []
+	}`
+
+	feed, err := Parse("https://example.org/feed.json", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.FeedURL != "https://example.org/feed.json" {
+		t.Errorf("Incorrect feed URL, got: %s", feed.FeedURL)
+	}
+}
+
+func TestParseFeedWithRelativeFeedURL(t *testing.T) {
+	data := `{
+		"version": "https://jsonfeed.org/version/1",
+		"title": "My Example Feed",
+		"home_page_url": "https://example.org/",
+		"feed_url": "/feed.json",
+		"items": []
+	}`
+
+	feed, err := Parse("https://example.org/feed.json", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.FeedURL != "https://example.org/feed.json" {
+		t.Errorf("Incorrect feed URL, got: %s", feed.FeedURL)
+	}
+}
+
+func TestParseFeedSiteURLWithTrailingSpace(t *testing.T) {
+	data := `{
+		"version": "https://jsonfeed.org/version/1",
+		"title": "My Example Feed",
+		"home_page_url": "https://example.org/ ",
+		"feed_url": "https://example.org/feed.json",
+		"items": []
+	}`
+
+	feed, err := Parse("https://example.org/feed.json", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.SiteURL != "https://example.org/" {
+		t.Errorf("Incorrect site URL, got: %s", feed.SiteURL)
+	}
+}
+
+func TestParseFeedWithRelativeSiteURL(t *testing.T) {
+	data := `{
+		"version": "https://jsonfeed.org/version/1",
+		"title": "My Example Feed",
+		"home_page_url": "/home ",
+		"feed_url": "https://example.org/feed.json",
+		"items": []
+	}`
+
+	feed, err := Parse("https://example.org/feed.json", bytes.NewBufferString(data))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.SiteURL != "https://example.org/home" {
+		t.Errorf("Incorrect site URL, got: %s", feed.SiteURL)
+	}
+}
+
 func TestParseFeedWithoutTitle(t *testing.T) {
 	data := `{
 		"version": "https://jsonfeed.org/version/1",
diff --git a/internal/reader/rdf/adapter.go b/internal/reader/rdf/adapter.go
index bc8c76ed..f90ebaca 100644
--- a/internal/reader/rdf/adapter.go
+++ b/internal/reader/rdf/adapter.go
@@ -24,18 +24,18 @@ func NewRDFAdapter(rdf *RDF) *RDFAdapter {
 	return &RDFAdapter{rdf}
 }
 
-func (r *RDFAdapter) BuildFeed(feedURL string) *model.Feed {
+func (r *RDFAdapter) BuildFeed(baseURL string) *model.Feed {
 	feed := &model.Feed{
 		Title:   stripTags(r.rdf.Channel.Title),
-		FeedURL: feedURL,
-		SiteURL: r.rdf.Channel.Link,
+		FeedURL: strings.TrimSpace(baseURL),
+		SiteURL: strings.TrimSpace(r.rdf.Channel.Link),
 	}
 
 	if feed.Title == "" {
-		feed.Title = feedURL
+		feed.Title = baseURL
 	}
 
-	if siteURL, err := urllib.AbsoluteURL(feedURL, r.rdf.Channel.Link); err == nil {
+	if siteURL, err := urllib.AbsoluteURL(feed.FeedURL, feed.SiteURL); err == nil {
 		feed.SiteURL = siteURL
 	}
 
diff --git a/internal/reader/rdf/parser_test.go b/internal/reader/rdf/parser_test.go
index 5009a412..021772b4 100644
--- a/internal/reader/rdf/parser_test.go
+++ b/internal/reader/rdf/parser_test.go
@@ -289,7 +289,37 @@ func TestParseRDFFeedWithRelativeLink(t *testing.T) {
 		xmlns="http://purl.org/rss/1.0/">
 		<channel>
 			<title>Example Feed</title>
-			<link>/test/index.html</link>
+			<link>/test/index.html  </link>
+		</channel>
+		<item>
+			<title>Example</title>
+			<link>http://example.org/item</link>
+			<description>Test</description>
+		</item>
+	</rdf:RDF>`
+
+	feed, err := Parse("http://example.org/feed", bytes.NewReader([]byte(data)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.SiteURL != "http://example.org/test/index.html" {
+		t.Errorf(`Incorrect SiteURL, got: %q`, feed.SiteURL)
+	}
+
+	if feed.FeedURL != "http://example.org/feed" {
+		t.Errorf(`Incorrect FeedURL, got: %q`, feed.FeedURL)
+	}
+}
+
+func TestParseRDFFeedSiteURLWithTrailingSpace(t *testing.T) {
+	data := `<?xml version="1.0" encoding="utf-8"?>
+	<rdf:RDF
+		xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+		xmlns="http://purl.org/rss/1.0/">
+		<channel>
+			<title>Example Feed</title>
+			<link>http://example.org/test/index.html </link>
 		</channel>
 		<item>
 			<title>Example</title>
diff --git a/internal/reader/rss/adapter.go b/internal/reader/rss/adapter.go
index 531cc53f..48def825 100644
--- a/internal/reader/rss/adapter.go
+++ b/internal/reader/rss/adapter.go
@@ -26,14 +26,15 @@ func NewRSSAdapter(rss *RSS) *RSSAdapter {
 	return &RSSAdapter{rss}
 }
 
-func (r *RSSAdapter) BuildFeed(feedURL string) *model.Feed {
+func (r *RSSAdapter) BuildFeed(baseURL string) *model.Feed {
 	feed := &model.Feed{
 		Title:   html.UnescapeString(strings.TrimSpace(r.rss.Channel.Title)),
-		FeedURL: feedURL,
-		SiteURL: r.rss.Channel.Link,
+		FeedURL: strings.TrimSpace(baseURL),
+		SiteURL: strings.TrimSpace(r.rss.Channel.Link),
 	}
 
-	if siteURL, err := urllib.AbsoluteURL(feedURL, r.rss.Channel.Link); err == nil {
+	// Ensure the Site URL is absolute.
+	if siteURL, err := urllib.AbsoluteURL(baseURL, feed.SiteURL); err == nil {
 		feed.SiteURL = siteURL
 	}
 
@@ -41,7 +42,7 @@ func (r *RSSAdapter) BuildFeed(feedURL string) *model.Feed {
 	for _, atomLink := range r.rss.Channel.AtomLinks.Links {
 		atomLinkHref := strings.TrimSpace(atomLink.Href)
 		if atomLinkHref != "" && atomLink.Rel == "self" {
-			if absoluteFeedURL, err := urllib.AbsoluteURL(feedURL, atomLinkHref); err == nil {
+			if absoluteFeedURL, err := urllib.AbsoluteURL(feed.FeedURL, atomLinkHref); err == nil {
 				feed.FeedURL = absoluteFeedURL
 				break
 			}
diff --git a/internal/reader/rss/parser_test.go b/internal/reader/rss/parser_test.go
index d9dacac6..e3f8450f 100644
--- a/internal/reader/rss/parser_test.go
+++ b/internal/reader/rss/parser_test.go
@@ -109,6 +109,100 @@ func TestParseRss2Sample(t *testing.T) {
 	}
 }
 
+func TestParseFeedWithFeedURLWithTrailingSpace(t *testing.T) {
+	data := `<?xml version="1.0"?>
+		<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+		<channel>
+			<title>Example</title>
+			<link>https://example.org/</link>
+			<atom:link href="https://example.org/rss " type="application/rss+xml" rel="self"></atom:link>
+			<item>
+				<title>Test</title>
+				<link>https://example.org/item</link>
+			</item>
+		</channel>
+		</rss>`
+
+	feed, err := Parse("https://example.org/ ", bytes.NewReader([]byte(data)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.FeedURL != "https://example.org/rss" {
+		t.Errorf("Incorrect feed URL, got: %s", feed.FeedURL)
+	}
+}
+
+func TestParseFeedWithRelativeFeedURL(t *testing.T) {
+	data := `<?xml version="1.0"?>
+		<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
+		<channel>
+			<title>Example</title>
+			<link>https://example.org/</link>
+			<atom:link href="/rss" type="application/rss+xml" rel="self"></atom:link>
+			<item>
+				<title>Test</title>
+				<link>https://example.org/item</link>
+			</item>
+		</channel>
+		</rss>`
+
+	feed, err := Parse("https://example.org/", bytes.NewReader([]byte(data)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.FeedURL != "https://example.org/rss" {
+		t.Errorf("Incorrect feed URL, got: %s", feed.FeedURL)
+	}
+}
+
+func TestParseFeedSiteURLWithTrailingSpace(t *testing.T) {
+	data := `<?xml version="1.0"?>
+		<rss version="2.0">
+		<channel>
+			<title>Example</title>
+			<link>https://example.org/ </link>
+			<item>
+				<title>Test</title>
+				<link>https://example.org/item</link>
+			</item>
+		</channel>
+		</rss>`
+
+	feed, err := Parse("https://example.org/", bytes.NewReader([]byte(data)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.SiteURL != "https://example.org/" {
+		t.Errorf("Incorrect site URL, got: %s", feed.SiteURL)
+	}
+}
+
+func TestParseFeedWithRelativeSiteURL(t *testing.T) {
+	data := `<?xml version="1.0"?>
+		<rss version="2.0">
+		<channel>
+			<title>Example</title>
+			<link>/example </link>
+			<item>
+				<title>Test</title>
+				<link>https://example.org/item</link>
+			</item>
+		</channel>
+		</rss>`
+
+	feed, err := Parse("https://example.org/", bytes.NewReader([]byte(data)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if feed.SiteURL != "https://example.org/example" {
+		t.Errorf("Incorrect site URL, got: %s", feed.SiteURL)
+	}
+}
+
 func TestParseFeedWithoutTitle(t *testing.T) {
 	data := `<?xml version="1.0" encoding="utf-8"?>
 		<rss version="2.0">